Pool Plumbing Valve Guide - INYOPools.com - DIY Resources (2023)

Pool Plumbing Valve Guide - INYOPools.com - DIY Resources (1)

Pool Plumbing Valve Guide

January 25, 2016 Matthew Simmons

Valves are an unsung hero of pool equipment because they allow us to control the flow of thousands of gallons water with the twist of a handle. However, the only time you most likely wondered how they worked was when they didn’t work. These pieces of metal and plastic have various designs and applications suited for specific jobs, and the key is knowing when to use which valve. This walk-through of the various types of swimming pool plumbing valves should give you the knowledge you need. Let’s begin!

Check Valve

Check valves are dandy pieces of machinery that serve the dual purpose of monitoring the flow and preventing the backwash of water. The check valve’s two most common designs are the spring and flapper regulated valve. Both do the same basic job, but just differently.

Flapper Check Valve

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Besides the funny name, I like this valve because it reminds me of a one-way doggie door. The spring loaded flap is tensioned to one port of the valve body. The flap opens as water pressure rises and will remain open as long as the flow is at proper rates. The flapper style has a sizeable viewing window for easy inspection.

Spring Check Valve

The spring check valve uses a unique in-line plunger to affect a sleek and effective design. The valve is plumbed with the plunger facing the flow of water. As your pump builds pressure, the plunger will open allowing water to pass. The spring check valve is available in various spring tensions so a user can adjust the flow needed to open the valve. Spring check valves are sold with varying spring tensions that allow you to determine how much flow it takes to open the valve.

Most common spring tensions:

  • ½ lb.
  • 1 lb.
  • 2 lb.

The spring check valve is available in an opaque or clear housing. The latter allows you to determine flow and valve function at a glance.

Pool Plumbing Valve Guide - INYOPools.com - DIY Resources (4)

When to Use It

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The check valve’s intended purpose is to prevent backwash. For those of you who have never shared a soda with a friend, backwash is when a pipe loses pressure causing the contents of the pipe to recede to the source. Or, if you want a more dramatic explanation: the fluids withdraw from WHENCE they came! Not only is this bad for your fountain drink, but it is terrible for pool equipment too.

Most pools use a chlorinator system (salt or tabs) that is plumbed last in your series of filtration equipment. This placement puts the chlorinator directly after your pool heater, heat pump or chiller and squarely in the crosshairs of your chlorinator’s super chlorinated backwash. Chlorine in its concentrated form is super corrosive and damaging to metals, especially the fragile conducting metals found within the heating equipment. The only thing protecting your metal parts from destruction is the dilution of chlorine once it shoots back to your pool. Dilution and the process of killing microbes deplete the strength of chlorine by the time it cycles back to your filter equipment.

When your pump turns off, the water in your chlorinator may recede to your pool heater where it will sit for hours until your pump restarts. During that time, the super chlorinated water has time to gnaw, chew and munch away at your copper heat exchanger. The cause and effect of that process is a very expensive heat exchanger replacement sooner than necessary.

Also, check valves (usually the spring type) are used as bypasses to aid in heating and salt chlorinators. Some manufacturers suggest a bypass to your heater’s plumbing to slow the flow of water through the heat exchanger. The lower flow keeps the water in contact with the heat exchanger for longer that allows for a more efficient transfer of heat. The same logic is used in salt chlorinators and the titanium cell plates, most notably on the Autopilot systems that include a bypass manifold, seen in the. The bypass manifold diverts flow equivalent to 20 GPM (or so) through the cell, any flow above that tolerance will open the check valve at the bottom of the loop, bypassing the cell. The slower flow allows for a thorough chlorination of the water and prevents undue wear on the cell’s plates.

Check valves are normally installed horizontally, and a few can be installed vertically. Check the manufacturer’s installation guide if you need a valve for vertical installation.

Shut-off Valves

Shut-off valves are used to stop the flow of water through one or more pipes completely. Thus the name shut-off valve. Valve manufacturers are not very inventive when it comes to names, but they are crafty when it comes to design. So, let’s dig in.

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Diverter Valve

The diverter is the workhorse of the pool valve family. If you have an in-ground pool, there is a high probability you have one of these bad boys on the plumbing system. These valves contain a diverter that slides over the port holes to close it or to the side to allow full flow.


  • They are available in a two or three port version.
  • The two-port is essentially a 1-in and 1-out that allows the user to shut down flow completely.
  • The three-way or T-style has one in-port and two out-ports that allow flexibility to isolate flow to one port or shut off flow to both out, but closing the inlet.

When to Use It?

Diverter valves can be used on PVC plumbing for in-ground or above ground pools. They can be fitted vertically or horizontally. There are two types of diverter valves – the positive seal, and non-positive seal.

  • Positive seal – Completely seals the valve opening preventing any seepage. The diverter gasket is more robust and protrudes from the face of the diverter to create a firm seal.
  • Non-positive seal – Allows some water to pass through the diverter when closed, making it not ideal for standard plumbing use. Non-positive valves are normally found on systems with solar heaters so water can drain from the solar panels even when a valve is set to “CLOSED”.

Gate Valves

Gate valves are a simple on/off flow regulator used mainly on above ground pools, but they can be found on older in-ground installations. These valves should not be used to throttle water flow, but only as a purely on/off regulator. The valve’s design consists of the body and the internal gate, with the handle and stem.

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The gate is a wedge or circular plate that is risen or dropped to regulate the valve. Gate valves can serve a dual purpose of an adapter and a valve. The in the section shows the various port style combinations available. The valve can connect threaded PVC to a hose, slip PVC to threaded, and can even have a union adapter on one side with your choice of connection on the other.

When to Use It?

Gate valves are installed on above ground pools for their ability to shut off hose or PVC piping while filtering equipment is serviced.

Ball Valves and Butterfly Valves

I mention these two in the same breath because they do the same task in similar ways. The ball and butterfly valves both use a spinning element/insert to stop or release the flow of water with a quarter turn of the handle. The ball valve uses a metal (usually copper) sphere with a cored center to allow water through.

Butterfly valves use a spinning paddle plate to adjust water flow. A quarter turn of the handle spins the paddle sideways releasing the flow. Butterfly valves are unique in the sense that their element remains in the direct path of flow at all time. The gate, diverter and ball valves element for stopping water only in the path of water when the flow is being actively blocked.

When to Use It?

(Video) How To: Repair a Diverter Valve

Butterfly Valves are most commonly found in commercial pools whereas ball valves are used as shut-off valves on small water features.


Should skimmer valve be open or closed? ›

For proper water circulation, it is best to position the flap so that it is about 2/3 closed. This will allow for more flow through the main drain than through the skimmer, which will promote a "bottom-to-top" circulation throughout the pool.

What valves should be open when backwashing pool? ›

Turn the multiport valve to Backwash. If you have a push/pull valve, open the backwash gate. Turn the filter system back on, and let it run for about two minutes. This will allow pool water to flow out of the backwash valve or port.

What valves to close when vacuuming pool? ›

Ensure that the valve to the skimmer that the vacuum hose is connected to, is fully open. Slowly close the Main Drain valve about halfway, this is the optimal setting for vacuuming.

Should all my pool valves be open? ›

A normal pool valve setting would have the skimmer valve(s) fully open, main drain half-open and spa drain fully closed. To operate a suction pool cleaner or manually vacuum the pool, you can close other skimmers, or close the main drain, to obtain more suction through the skimmer you are using.

How do I know if my pool is circulating? ›

To observe a pool? s circulation, try the ping-pong ball test. This involves tossing at least a dozen ping-pong balls into the pool and watching where they travel. The balls should travel in a clockwise pattern and eventually end up in the skimmer basket.

Should water valve be fully open? ›

Similar to gate valves, ball valves should be all the way open to allow the full flow of water or all the way closed to restrict all water from flowing.

What is the second hole in a pool skimmer for? ›

When you closely inspect your pool skimmer, you will notice two holes. One hole goes directly to your pump. The other hole goes down to the floor drain, usually located in the middle of your pool. The diverter's primary function is to divert water suction from the skimmer to the floor drain.

Do you close any valves when backwashing pool? ›

BACKWASH: Use this setting to reverse the flow in the filter and send water out of the waste line. Make sure valves are open and your backwash hose is rolled out. CLOSED: Put here to close off flow from the pool, usually to work on the equipment, or prevent backflow of water out of the filter.

How do you know if your skimmer is working properly? ›

When skimmers do not work the most common problem is a lack of air. If air is being properly mixed with the water your skimmer should be producing bubbles. If your skimmer is producing bubbles then chances are there is nothing wrong with your skimmer. It may just need to break in, be cleaned, or be readjusted.

How much does it cost to replace a pool valve? ›

The cost to replace a main water shut-off valve typically ranges anywhere from $150 to $600, with an average cost of around $285. However, the cost of main water shut-off valve replacement can vary quite a bit, depending on the size of the valve and its location.

Can I fix a diverter valve myself? ›

We wouldn't recommend fixing the diverter valve yourself. If you think there's a problem, you should call a suitably qualified engineer to have a look at it for you. The engineer will run a check to test whether it's the diverter valve that's the issue and not another underlying problem.

Should I vacuum my pool on backwash or waste? ›

To begin vacuuming your pool:

If you do have this option, it is highly recommended that whenever you have algae, you will need to vacuum to waste. This option allows you to vacuum the algae up and send it out through the backwash line, avoiding getting algae into your filter sand.

Should you rinse or backwash first? ›

Backwashing reverses the flow of water, lifts up and flushes the sand, and then expels the dirty water via a waste line into the ground or drain. In order to prevent residual blow back into the pool, once you've finished backwashing it's highly advisable to rinse the filter.

Do you close skimmer when vacuuming pool? ›

Now, here answers the question earlier: do you leave skimmer basket in when vacuuming pool? YES, you need to remove the skimmer or strainer basket before attaching the open end of the hose to the inlet. Finally, plug the open vacuum hose into the suction port.

Is a skimmer float valve necessary? ›

The main drain should circulate Around 75% to 80% of the pool water the skimmer is only capable of circulating the top 25% of water. If you don't have this device your pool is only getting Partially filtered and It can cause algae, cloudy water and chemistry problems.

Is it better to let pool pump run all the time? ›

Every pool should cycle through all of its water at least once a day, so most pool owners will want to run their pumps for at least 4-8 hours daily. But you don't have to run those 4-8 hours all at once so you can split the pump time up at different parts of the day to ease your energy budget.

Should pool be on main drain or skimmer? ›

Skimmer Vs. Drain. If the pool receives a lot of leaves and other debris, more suction may be required at the skimmer than the main drain to adequately strain debris floating on the surface. Conversely, if dirt on the bottom of the pool is the principal contaminant, more suction is required at the main drain.

How many hours a day should you circulate your pool? ›

Water circulation is important for a healthy and safe swimming pool. A pool with proper circulation has fewer issues with cloudy water or pool algae. Keeping your pump and filter system running for at least 8 to 12 hours is the best way to keep your pool safe and clean.

How do you fix poor circulation in pool? ›

To ensure proper circulation, you need to switch on the pump for at least 8 hours a day. This ensures the pool circulation is effective. Make sure you size the pump, i.e: get a pump according to your pool volume. If your pool capacity is 10,000 gallons, then you need to divide 10,000 by 480 (8 hours x 60 minutes).

How many hours should I circulate my pool? ›

On average, you should run your pool pump around 6-8 hours per day during winter and 10-12 hours per day during summer. Note that you need to run your pool pump longer during summer because algae grow more in warm temperatures.

Can you open a water valve too much? ›

To turn the water back on, slowly turn the valve one-quarter turn counterclockwise. Warning: Turn the valve slowly to turn on the water to your home. Opening the valve too quickly can result in damage to the pipes in your home. Be sure to also clear any air from the water lines.

Can you open a water valve too far? ›

A typical 1″ main control valve for a water line will take about six full turns to fully open. Stop turning as soon as there is any resistance. Turning the handle or stem too far with excessive pressure can cause damage and very often will cause a leak.

What is pool skimming? ›

Pool skimming implies cleaning various debris from the pool, such as leaves, flowers, insects, hair, etc. It's an essential step to keep the pool water clean and ready for the next swim.

Can you snake a pool skimmer line? ›

Quickly remove the ball, and hopefully you'll see debris coming out. If not, you can try snaking out the pipe. If you run a snake down the skimmer, you likely won't be able to grab the obstruction, since it will probably be either a clump of leaves or a rock that you sucked up while vacuuming.

How far between skimmer and return? ›

The return inlets placement shall be as follows: 1. Wall inlets shall be placed within five feet of each pool corner and at least five feet from a skimmer. (i) Wall return inlets for the circulation system shall be designed to include directionally adjustable fitting to provide effective distribution of water.

What happens if you vacuum your pool on backwash? ›

Yes, we recommend backwashing after you vacuum your pool. This allows the filter to shoot out any dirt / debris you have vacuumed up. Don't forget to set your filter to “rinse” for 30 seconds after backwashing!

How long do you rinse after backwash? ›

Turn the lever to BACKWASH. Open the valves to the suction and return lines. Start the pump. Rinse the filter for about 1 to 2 minutes or until the water in the sight glass is clear.

What happens if you backwash your pool too long? ›

As eluded to above, if you backwash your pool pump for too long, it runs the risk of introducing air into the system. Air pockets can cause pumps to lose the constant flow of water that they need to keep working. If this happens to your system after a backwash, you may need to prime your swimming pool pump.

Will skimmer work if water level is high? ›

It is recommended you have your swimming pool water level between one-third and one-half up the pool skimmer box opening. If the level is higher than that, it may slow or even stop debris from being pulled into the skimmer box through the plate or valve.

Do you put chlorine in skimmer or float? ›

Put your chlorine tablets in the skimmer.

Your pump and filter are the two driving forces that keep your pool clean and healthy. If you put your tablets in the skimmer, the tablets will dissolve and form highly acidic water. This acidic water can go straight into the filter and compromise its internal parts.

How long does inground pool plumbing last? ›

There are more than 2 million miles of PVC pipe in service today, and rigid PVC pipe (Schedule 40) is the standard for pool plumbing pipe. Highly durable rigid PVC pipe is capable of a lifespan of over 75 years when properly installed.

How long do pool valves last? ›

Pool valves tend to last between 5-7 years before the exterior plastic parts need to be replaced. As long as the internal parts are working handles can be replaced. If the valves are older than 10 years you may want to replace the whole thing versus replacing just handles.

Do you need check valves on pool plumbing? ›

Pool valves are essential in the operation of the plumbing system of your swimming pool. They ensure proper water circulation, which, in turn, keeps your pool clean all the time. Check valves, for instance, to prevent water from going back to the pump.

What is a diverter valve look like? ›

In most cases, the diverter valve looks like a pin located on the bathtub faucet spout, but it might appear as a third handle or lever. When the valve is activated, a rubber stopper plugs the water flow and the pressure sends the water through the showerhead.

What are the symptoms of a faulty diverter valve? ›

A diverter valve may be faulty if the hot water taps still work while the radiators do not turn on. Another sign of a faulty diverter valve is if you only can only get lukewarm water from your taps.

Is a diverter the same as a valve? ›

The main difference between a diverter and a transfer valve is how they direct the water supply. Diverters switch the flow of water between a tub and shower — either the showerhead or the tub faucet gets the water flow. Transfer valve sends water to multiple outlets at the same time.

Which direction valve is open? ›

In most cases, the master shutoff valve to the home will have a wheel (gate valve) or a straight handle (ball valve). Gate valves (pictured to the right) are operated by turning the wheel clockwise until the water is off. Ball valves are operated by turning the handle a quarter-turn clockwise until the water is off.

What does O and S mean on a water valve? ›

One type of valve commonly used to control water flow to fire sprinkler systems is known as an OS&Y gate valve. OS&Y means “outside stem and yoke” or "outside screw and yoke". OS&Y gate valves operate by opening and closing via a gate, which lowers into or rises out of the valve.

How do you determine the direction of flow on a control valve? ›

The most common flow control used is a needle valve integrated into a fitting. A bypass check valve will also be integrated in the fitting to permit free reverse flow. The direction of free flow should be indicated on the body of the fitting.

Should return jets face up or down in a pool? ›

It's good practice to point your return jets in a direction that will circulate the water in your pool. If your pool only has one jet, point the jet toward the skimmer and downward. This will circulate the water, and push the water at the bottom of the pool to the surface.

How can I improve the circulation in my pool? ›

To ensure proper circulation, you need to switch on the pump for at least 8 hours a day. This ensures the pool circulation is effective. Make sure you size the pump, i.e: get a pump according to your pool volume. If your pool capacity is 10,000 gallons, then you need to divide 10,000 by 480 (8 hours x 60 minutes).

How high should pool pressure be? ›

Most filter systems are designed to operate in the 5-15 psi or 10-20 psi range. The way to find out your particular correct pool filter pressure is to clean or backwash the filter thoroughly and empty the pump and skimmer baskets.

Which is better to drain the pool waste or backwash? ›

Drain/Waste: Opting the drain or waste setting will remove pool water without forcing it through the filter. Backwash: This clears out any debris, dirt and other contaminants that may have accumulated on the filter. Closed: if you choose this setting, then the flow of water to the pool and filter will be stopped.


1. How To: Clean Out A Pool Pump Impeller
(Inyo Pools)
2. How to: Replace a Pool Pump Motor
(Inyo Pools)
3. How To: Replace a Pool Pump With an Energy Efficient Pool Pump
(Inyo Pools)
4. How To Manually Vacuum A Pool
(Inyo Pools)
5. How To Fix A Draining Spa (Check Valve Repair)
(Inyo Pools)
6. How To Drain and Clean A Swimming Pool
(Inyo Pools)


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