Reverse Osmosis System Installation Instructions

By h2osplashwaterfilters

Reverse Osmosis System Installation Instructions

Reverse Osmosis System

Reverse Osmosis System

Note: These instructions apply to 3, 4, 5, 6 and 7 stage RO Systems. If your system is a 4, 5 or 6 stage system, some of the instructions included herein will not apply to your system. As an example, if your RO System does not have a Booster Pump or a Permeate Pump, simply skip-over the comments about a Booster Pump or a Permeate Pump. The same applies to other options in these instructions.

Item 1 – Location
In the real estate business they commonly say “location, location, location” is the most important thing. That is also somewhat true in positioning a Reverse Osmosis unit. A Reverse Osmosis (RO) System is designed to fit under most sinks. It can also be installed in the utility area or in a basement. Of course the tubing will then need to be extended up to the faucet and/or ice maker. It can be installed in any location that will not present a problem of freezing in the winter. Basement installations will provide easy access for filter changes and often a basement location will provide a better connection access to a refrigerator icemaker or a second faucet location. One other important factor is that it does not take up valuable space under your kitchen sink. In situations where cold weather is not a factor, an attached garage might offer a good location. The vast majority of RO units are installed under the sink, correspondingly, these installation instructions will address an under the sink installation.

Item 2 – Preparation
Remove all items from the shipping package. Some models of Reverse Osmosis systems are shipped fully installed. If the model you have purchased has the filters and membrane installed, you can skip Item Three and go to Item Four.

Sediment and Carbon

RO Membrane

Item 3 – Install Filters and RO Membrane
Install filters and membrane in housings. The white 10″ sediment filter goes in the first filter housing. This is the inlet feed water and is the one on the right. The 10″ carbon block filter goes in the second filter housing (for RO systems with three pre-filters, install a second carbon block filter in the third housing). This would be the second housing on the left (second and third on a unit with three pre-filters). The RO membrane will be installed in the horizontal housing on top of the pre-filter housings. Be certain to screw all housings to a tight position. The rubber “O Rings” will create a seal when securely tightened. If your system has an inline DI filter, please review the installation instructions under DI .

Item 4 Now let us get aquatinted with some of the parts on the system that are already installed and ready to operate.

ASO Valve

Above is the ASO valve. It is positioned on the mounting bracket just behind the RO membrane housing (see the diagram for the RO membrane housing location). The ASO (Auto Shut Off) valve is the monitor for starting the RO system and stopping the production when the storage tank is full. When the storage tank drops to 65%, the ASO opens and allows the incoming water to rush in through the ASO to the RO membrane housing where the system purifies the incoming water. When the tank is full, the ASO valve closes and the incoming water is no longer allowed to enter and production of purified water ceases. A few comments to identify the connections to the ASO valve;
1. The Red tubing coming from the last pre-filter attaches to the “in” high pressure on the ASO.
2. The Red tubing attached to the “out” on the ASO goes to the inlet on the RO membrane housing.
3. The Blue tubing coming out of the RO membrane housing goes to the “in” on the low pressure of the ASO. The fitting that screws into the RO membrane housing for the Blue tubing to attach onto is also the check valve.
4. The blue tubing coming out of the ASO goes to the tee on the inlet of the in-line carbon filter (if your unit has an in-line carbon – post filter) or directly to the storage tank when an in-line carbon is not present.

Flow Restrictor

Above is a picture of the flow restrictor. Fitting Connector Flow Restrictor Combo - This type of flow restrictor is a fitting that is inserted into the drain outlet on the membrane housing. It serves three functions. Its first function is as the connection between the RO membrane housing and the drain tubing. Secondly, it is the flow restrictor wherein it regulates the flow of water over the membrane to obtain the best performance from the membrane. Third, it is also a check valve on the drain line. The check valve safety feature is one aspect of the drain line that is overlooked by many manufacturers and RO system owners. Without a check valve in the drain line, if the drain plugs, the drain line will back up into the RO membrane and create all sorts of problems. Correspondingly, we encourage RO owners to give consideration to installing some type of check valve in the drain line for safety purposes.

Check Valve

Above is a Check Valve .  This elbow type check valve is installed into the RO membrane housing where the product water comes out of the RO membrane. The check valve is inside the elbow fitting. This male elbow connector screws into the 1/8 inch opening on the RO membrane housing and the other end of the elbow is where the ¼ inch tubing is inserted. The ¼ inch tubing connects to the ASO valve.

Item 5 – Mount Unit
If space permits and you desire to hang the filter housings on the side of the cabinet, use the holes in the filter housing mounting bracket to mark the locations to drill to install (2) mounting screws and screw into side wall. There should be sufficient clearance below the bottom of the housings, so that you can place a container to catch water when the filters are being replaced. Position the unit and hang the system to see if sufficient room was allowed. The tank needs to be positioned on firm surface. Access to the shut-off valve on tank is important and you should not obstruct the shut-off on cold water line. The tank can be set upright or laid horizontally. The closer the tank is to the faucet, the better the flow will be, however you can position the tank as much as 50 feet from the faucet. Remove and set aside filter housings and tank for now.

Saddle Valve

Item 6 – Self Piercing Tap or Supply Valve Adapter
Your System is equipped with a “Self Piercing Tap Valve”.
When installing the “Self Piercing Tap Valve” on copper lines be certain to install it in-line after the cold water shut-off valve ( never install on the hot water line). Mount and tighten the “self piercing valve” on the copper line in an easy to reach location. Turn the saddle valve clockwise all the way in. This will drive the sharp end of the piercer into the copper tubing and will pierce a tiny hole. When the saddle valve has been turned all of the way in, the valve is in the “off” position for your new RO system. Do not do anything further with the saddle valve at this time. Leave it like this until later in the installation process.

Drain Clamp

Item 7 – Drain Saddle
Sink With Disposal – The vertical pipe above the horizontal pipe from garbage disposal is the best choice for a location to install the drain saddle on a sink with a disposal. For a sink without a disposal, the best choice is the vertical drain pipe as high above the water level in the trap as possible. Try to keep the saddle as far away from the dish washer and waste disposal drains as you can. Do not use the body of the saddle as a guide for your drill. The threads of the drain saddle may be damaged.
To To install, drill a 1/4″ hole through one side of the drain pipe. Remove any “burrs” created from drilling. This will help prevent debris from plugging drain hole. Align and center gasket on hole between pipe and drain saddle. Align the hole in the drain saddle with the hole in the drain pipe. Tighten down the drain saddle firmly.


Item 8 – Install R.O. Faucet
Many sinks have an extra hole for the mounting of additional faucets, sprayers or soap dispensers. If your sink does not have an additional hole, you will need to drill a hole as follows:
First, determine the location for the faucet hole. Before you begin drilling, check underneath sink making certain there are no obstructions.
Stainless Steel Sink. Carefully mark the faucet location, making certain that it is far enough away enough from the regular water faucet(s) so that they don’t interfere with the operation of each other. Be certain there is sufficient clearance to tighten the lock nut from below, before you begin the drilling procedure. Use center punch to make an indentation in sink surface to help hold alignment of to drill the hole. Drill a 7/16″ hole, and then smooth out rough edges with a file if required. Porcelain Coated Sink. The manufacturer recommends to have this type of sink professionally drilled because of possibility of chipping or cracking. If you are attempting to drill, use extreme caution. Use a Relton Cutter with adequate cooling lubricant.
You may also install the faucet directly into the countertop if you do not want to drill the sink. Position the faucet at the location to be drilled to make certain that the end of the spout will reach over the sink. Feel underneath the countertop to make certain there is no obstruction that would prevent proper faucet installation.

Item 9 – Installing Faucet

Once the hole is prepared, assemble those parts of the faucet that belong above the sink. Remove the nut from the threaded portion of the faucet (underneath the faucet body). Next, slide the middle sized black flat washer on to the threaded portion of the faucet. Then add the chrome cover followed by the larger black washer. When you have these three items added to the faucet you are ready to insert the faucet into the hole discussed in Item 7 above. The black washers will provide the seal for the faucet.
From underneath the sink, slide on the thick black plastic washer first, then slide on the lockwasher and then attached the nut. Tighten firmly into place once the faucet is properly aligned.

Faucet Tube Connect 1/4″ tube to threaded connector on the bottom of the faucet. This is the center post of the faucet. Use supplied hex nut and plastic ferrule. Cut to length and connect the other end to the incoming water source (RO system, under counter filter etc.). Tighten firmly.

Storage Tank

Item 10 – Preparing The Storage Tank
Using Teflon tape, wrap the threads on the tank 5 or 6 times (don’t use any other type of pipe compounds).
Screw the plastic ball valve on to the Teflon taped threads on the tank (approximately 4 to 5 full turns – do not over tighten – ball valve can crack).
The tank is pre-charged with air at 7 psi when empty. Tank can be laid on its’ side (horizontal) if necessary – tank will hold between 2 to 3 gallons of R.O. water).


Item 11 – Tubing

Filter changing and servicing may require added tubing for better maneuvering. If the RO unit is going under the kitchen sink, our installers set the RO unit in the sink and measure tubing to reach from the sink to the four locations in the RO system (supply, tank, faucet & drain). That way they can bring the unit up into the sink to service and change filters with less mess. Therefore it is best to leave extra tubing and thereby make your servicing easier.

Supply Tube – (Red tube from self piercing tap or supply valve tee to RO pre filter housing).  Slide self piercing nut onto red tube.  Slide plastic ring (ferrule) over tubing with tapered end facing the seat of self piercing tap and place brass insert inside red tube.  Connect to self piercing tap and tighten with ½” wrench. Measure length of tubing needed for servicing as noted in paragraph above. Cut the tubing smooth, flat, and with a square cut being careful not to crush the tube.  Insert into quick connect fitting on first pre filter housing (sediment housing).

Tank Tube -  (Yellow tube) Place storage tank in final location under the sink. Determine length of tubing needed for easy servicing. Connect yellow 1/4 inch tube to tee fitting on the end of the carbon post filter. Push in approx 5/8” to stop inside tee. Connect the other end of the tube to the tank valve using same method.

Faucet Tube – (Blue tube) Connect 1/4 inch tube to threaded connector on the bottom of the faucet. This is the center post of the faucet. Use supplied hex nut and plastic ferrule. Determine the length of tubing required between the faucet and the “out” fitting on the carbon post filter. If your system has a UV light, the tube will connect to the UV light fitting instead of post carbon fitting.

Drain Tube – (black tube) Slide black nut on black tube and connect to the drain saddle fitting and tighten nut firmly by hand. Determine length of tubing needed for easy servicing. Locate drain fitting on membrane housing (only fitting with nothing connected to it). Connect and hand tighten.

1 GPM UltraViolet Light

Item 12 – Ultraviolet Light System

If your RO System has an Ultraviolet unit installed, you will be removing 99.9% of harmful bacteria (E Coli, Coliforms, Viruses Fungi, Algae, Spores etc.). The UV unit has been installed on your system with clips attached to the RO membrane housing. The flow of water will enter the UV unit after it has been through the RO membrane and the polish filter and just prior to the water going to the faucet and refrigerator. This flow pattern will eliminate any bacteria that might still be in the water after going through the RO system or buildup in the system or storage tank.

Booster Pump

Item 13 – Booster Pump, Transformer and Shut-Off Switch

A Reverse Osmosis membrane operates best with 50 or greater PSI and your RO System will provide quality water and improved quantity at higher PSI levels. Booster Pumps have installation instructions and a diagram showing the RO System layout for the most efficient use of the Booster Pump.

Booster Pump

This booster pump is designed to accomplish auto suck and it has been 100% tested to insure extended life.


The transformer has an input of  AC 110 V and output of DC 24 V. 100% factory tested.

Tank Shut-Off Switch

The switch turns off the booster pump when the tank is full (on at 30 psi and off at 50 psi). Closed switch can be set at various shut-off pressures. 100% factory tested. Quick connect fittings.

DI Resin

Item 14 – DI, KDF and other Resin Options

We offer two types of canisters to contain resins for specific situations, both are refillable canisters. The in-line canister has female ¼ inch threads on each end to attach a male connector to the tubing. The in-housing type canister is placed inside a standard housing with the resin installed inside the canister and the canister has the appropriate flow through it to force the water through the resin inside the canister. If your RO system has one of these canisters installed, the directional flow of the water through the system will set-up when the unit arrives. When the resin is depleted and requires replacement, you will remove the canister and dispose of the old resin and refill the canister with new resin.

Item 15 – System Start-Up Instructions

Check to be certain the storage tank valve is turned off so that no water may enter tank. Turn on the cold water supply valve to the sink. Next, check for leaks around the supply valve adapter or self piercing valve (which ever you have installed).
Open the R.O. faucet you have installed on the sink. Open the valve on the supply valve adapter or self piercing tap to turn on water to the RO system. You will hear water gurgling and filling the RO system. Water may take 10-15 minutes before dripping out faucet and at first may be dark in color. Let the water drip out of faucet for a minimum of 15 minutes and then close faucet.
Open ball valve on storage tank. Let tank fill for 6 to 10 hours (if you are changing filters, your tank may already be full, so you would not need to wait). Then open R.O. faucet. Drain the tank completely (about 15 minutes). When you have completely drained the tank, shut the R.O. faucet off. Let the RO system fill the storage tank again and then drain the tank in 6 to 10 hours.
Check for leaks daily for the first week and occasionally thereafter


Install a Union Tee on the tubing going to the faucet. Run a ¼ inch polypropylene tube up to 30 feet from the RO system to connect to the refrigerator. If you are using over 30 feet of tubing, it is best to use 3/8 inch tubing. DO NOT USE COPPER. Be certain to have the recommended manufacturers water pressure going to your refrigerator.

For more efficient servicing of the refrigerator, it is suggested to install a ball valve in the tube going to the refrigerator. Turn the ball valve off during startup and leave it off until start up procedures are completed  and the RO storage tank is completely full and ready to drink. IMPORTANT Never turn the ice maker on until you have a full storage tank of water to avoid damaging the ice makers solenoid.

Item 17 ‑ Filter Service Life And Change Cycle

Sediment Pre‑Filter Change every 6 months (more often in areas with high sediment or iron content in the water).

Carbon Block Pre‑FilterThese filters should be changed every 6 months. Carbon block filters are the workhorse of the pre‑filter system and remove chlorine and other contaminants that can be harmful to a TFC RO membrane. Therefore, changing carbon pre‑filters insures extended life for the RO membrane and provides quality drinking water.

R.O. MembraneThe R.O. membrane should be changed when the rejection rate falls to 88% to 90%. The rejection rate should be tested every 6 months. The membrane can last up to 5 years (perhaps longer) depending on the water quality, the hardness of the water coming into the system and the frequency of filter changes. The sure way to know when it is time to change the membrane is to know when the rejection rate of TDS falls below 88%. To determine the percentage of rejection, you will need a TDS meter to test the incoming water (prior to the RO system) and then compare it to the TDS of the water from the RO faucet. When the TDS of the water from the RO faucet is more than 12% of the TDS of the incoming water, it is time to change the RO membrane as your rejection rate has dropped below 88%.

Carbon Post Filter ‑  If your RO system is equipped with a carbon post filter, you should change this filter every 12 months to insure quality water. Change this filter everyother time you change the pre‑filters.

In‑Line Refillable DI Filter ‑   If your RO system is equipped with an in‑line refillable DI (Deionization ‑ Demineralized) mixed bed resin filter, the DI resin should be changed every 6 months. There are several factors that could alter the required frequency of changing the DI resin. The # 1 and most important factor is the TDS required. If your usage requirement is for at or near zero (0) TDS, a DI filter is the answer. However, the changing of the DI resin will vary depending on the incoming water (prior to the RO system), the rejection rate of your RO system and your TDS requirements. A TDS meter will be a requirement if your usage needs are at or near zero (0).

In‑Housing Refillable DI Filter –   If your RO System is equipped with an in-housing DI canister such as the picture in # 14 above, the comments about the In-Line Refillable DI Filter will apply to your DI canister.

RO Membrane/Filter Package

Item 18 ‑ RO Membrane and Filter Replacement

On most RO systems, the sediment pre‑filter is the first vertically housing mounted under the horizontal RO membrane housing. In a standard 4 stage system there will be two vertical housings and in a standard 5 stage or six stage RO system there will be three vertical housings. The second vertical filter on a four stage RO system is a carbon block pre‑filter. In the 5 stage and six stage systems there is an additional vertical carbon block pre‑filter. As noted above, the RO membrane is in the horizontally mounted housing that has an end cap that unscrews. Mounted on top of the RO membrane housing, will be the post carbon filter or the DI refillable filter or both. The following information will identify the procedures to follow in replacing each of these components.

Replacing The Pre‑Filters ‑   Turn the valve to the off position on the supply valve adapter or self piercing valve (this is your inlet water to the RO system). Turn the storage tank ball valve to the off position. Open the R.O. faucet to help de‑pressurize the system. Using the filter wrench, unscrew the filter housings by turning them in a counter clock wise direction. Remove old filters (perhaps it is best to do one housing at a time and then you will know which type filter came out of the housing you are working on), then discard the old filter. Clean filter housings (sumps) with warm soapy water. Rinse out the soapy water and then add two table spoons of liquid household bleach and fill with water. It is best to leave the bleached water in the housings for 5 to 10 minutes. Then empty the housings and rinse well with tap water. Insert new filter into the housing. Avoid touching the filter by using the wrapper to place the filter into the housing. Your hands could cause bacteria that will grow and foul the water. Replace the O rings as required. Be certain the O ring is clean, lubricated and seated properly before tightening. Use some Vaseline or silicon‑based lubricant and be certain that you have properly placed the O ring in the housing grove. Use a filter wrench (or by hand) to screw the housing back into place by turning it from left to right ‑ counterclockwise ‑ (Do not lay the unit down while screwing it in, the unit should be stand upright to prevent the O‑ring from slipping). Repeat this procedure for each pre‑filter on your RO system.

Post Carbon Filter ‑ Some reverse osmosis systems require polishing filters with threaded connections, others require polishing filters with quick‑connect fittings.

Threaded Connections ‑   Unscrew white plastic nut from both ends of post filter. Then remove the clear plastic tubes. Next, unscrew and remove the plastic fittings from each end of the filter. Dispose of the old filter. Now, wrap the fittings with Teflon tape and re‑install a fitting into each end of the new post filter. Do not apply too much pressure when you tighten the fittings into the filter. Make certain that the arrow on new filter is going with flow of water toward the faucet. Tighten the white plastic nuts to both ends of the new filter. You should turn approximately 1 1/2 to 2 more full turns. Be careful to not over tighten either the fittings or the attaching nuts.

Quick Connect ‑   To remove the tubing, push the gray collette in towards the filter and then pull the tubing out. Dispose of the old filter. To install the new filter, simply push the tubing all the way into the Quick‑Connect fitting.

Refillable In‑line DI Filter The Post Carbon Filter comments about threaded and quick connect fittings applies to these filters as well. However there is a difference once you have removed the tubing from the filter. Post Carbon Filters are disposable filters. Refillable DI filters are of course as the name implies, refillable. Once the tubing has been removed, remove the cap on the filter by turning it in a clock wise direction. Remove the old (spent) DI resin and replace it with new DI resin. Once you have the new resin installed, carefully reinstall the screw off cap making certain that the filter is properly in place on the inside of the cap.

R.O. Membrane Turn the valve off at the storage tank and also turn the inlet water off at the supply valve adapter (or the self piercing vale which ever you have installed) and then open the RO faucet. Next, disconnect the tube going into the end of the membrane housing on the end that has only one tube going into it. Unscrew the end cap of the membrane housing. Be prepared as water will pour out. Remove the old membrane (removal may require a pliers to pull the membrane out) and clean the membrane housing with warm soapy water. Membranes must remain moist at all times once wetted (installed). Insert the new membrane in the direction of the arrow on the membrane. The end with the two small O rings goes in first. The end with the large rubber ring (brine seal) goes in last, next to the removable end cap. Push firmly! Next, screw the end cap back on and reconnect the tubing to the fitting on the cap end of the membrane housing. Open the storage tank valve and the supply valve adapter (or self piercing valve). Drain the storage tank. Allow the storage tank to fill 3 times and empty (drain) it twice and then the third tank will be ready for drinking water usage.

Item 19 – Self Piercing Valve

When installing the “Self Piercing Tap Valve” on copper lines be certain to install it in‑line after the cold water shut‑off valve (never install on the hot water line). Mount and tighten the “self piercing valve” on the copper line in a easy to reach location. Turn the saddle valve clockwise all the way in. This will drive the sharp end of a sharp metal pierce into the copper tubing and will pierce a tiny hole. When the saddle valve has been turned all of the way in, the valve is the “off” position for your new RO system. Do not do anything further with the saddle valve at this time. Leave it like this until later in the installation process.

Item 20 – Storage Tank Preparation

If your tank does not have the ball valve installed, wrap the threads on the tank with Teflon tape (do not use pipe compound). It is best to use 5 or 6 rounds of Teflon tape to wrap the threads on the tank.

Install the ball valve on the Teflon taped threads on the storage tank. Tighten until secure but do not over tighten and damage the ball valve.

The storage tank has been pre‑charged with air at 7 psi when the tank was empty. This tank can be laid on its’ side if necessary. Remember this is a bladder tank and the more air that is inserted into the tank, the less water capacity the tank will have.

The RO system comes with a 4.5 gallon storage tank. Should your water usage require a larger storage tank, visit our storage tank store to see larger storage tank options.

Tank Problem Solving and Maintenance

Low storage capacity in the tank is most usually the result of an under inflated storage tank. If when you activate the faucet, you can only get a few glasses of water at a time, empty tank air pressure is the first thing to check. Systems with under inflated tanks can continue to run too long and quickly foul a membrane, requiring membrane replacement. Systems that continue to run can also be in need of a flow restrictor.

Symptoms of RO storage tank low air pressure or bladder failure:

1. System Runs frequently

2. Dispensing is slow and with low pressure from the faucet

3. If the tank is still heavy, after opening the faucet and allowing all of the water to drain from the tank, you have a bladder failure.

Keep your system operating properly, check the tank pressure each six months when you change the filters.

Maintaining the proper pressure (7 to 10 PSI when empty of water) will help avoid the membrane and filters from prematurely becoming exhausted or fouled. It is important to monitor the pressure and correct it if it is not maintaining the proper pressure.

Proper tank pressure (7 to 10 PSI) needs to be maintained for the hydraulic functions of the water to work correctly within the RO system. Tank bladders can lose air pressure just like a tire looses air pressure.

Procedure For Checking Your Storage Tank Pressure:

1. Turn the water off on the RO System’s incoming water line.

2. Open the faucet on your RO System and allow the water to run until the flow stops, then close the faucet.

3. Turn off the tank valve.

4. Is the tank heavy ‑ does it have water in it? Does it weight about 15 lbs? If the answer is yes, you will need to replace the tank as the bladder will no longer hold water. 5. The tank has an air stem just like those on a car tire. Just like the auto tire, the air stem is covered. You will need to remove the cap before you can insert air into the stem.

6. If required, you will need to increase or decrease the pressure in the tank to the correct PSI (7 to 10 lbs.). You can use a standard bike pump or a compressor. This is a low pressure system so be careful when inputting additional air as over inflation can damage the bladder.

7. Then open the tank valve followed by opening the incoming water valve.

8. Permit the tank to fill, depending on your RO membrane size, this may take a few hours. When filled, determine if the system now operates properly after you corrected the air pressure.

If you still have a problem, you likely have ;


Reverse Osmosis tank bladders do fail, requiring replacement of the tank. If the bladder in the tank starts to leak air, and water enters the air side of the bladder, the tank will have to be replaced. As described above, open the faucet and drain all of the water from the tank. When you pick the tank up, if the tank feels heavy as if it is full even though you can’t get water out of the faucet, the bladder is ruptured. The air stem may show signs of dampness from the water that passed to the air side of the bladder. We offer Replacement RO Tanks.

Item 21 – Source of TDS (Total Dissolved Solids)

1. Some dissolved solids come from organic sources such as leaves, silt, plankton, and industrial waste and sewage. Other sources come from runoff from urban areas, road salts used on street during the winter, and fertilizers and pesticides used on lawns and farms.

2. Dissolved solids also come from inorganic materials such as rocks and air that may contain calcium bicarbonate, nitrogen, iron phosphorous, sulfur, and other minerals. Many of these materials form salts, which are compounds that contain both a metal and a nonmetal. Salts usually dissolve in water forming ions. Ions are particles that have a positive or negative charge.

3. Water may also pick up metals such as lead or copper as they travel through pipes used to distribute water to consumers.

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