How a Multiport Valve Operates

WRITTEN BY:  Inyo Pools

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There are three major types of pool filtering system: cartridge, sand, and diatomaceous earth (DE). Sand and DE filters use a multiport valve primarily to help clean or backflush the filter media. Cartridge filters do not have multiport valves. These filters are cleaned by removing the cartridge and spraying it with a garden hose. A typical multiport valve has 7 settings: filter, backwash, rinse, waste, closed, recirculate, and winter. This guide explains the function of these setting and shows how they circulate water in a typical sand filter. The operation of a DE multiport valve is very similar.


Step by Step


Step 1

There are five ports into and out of a typical multiport valve. Three are shown in this picture. The top left port, labeled "PUMP", brings unfiltered water in from the pump. The middle left port, labeled "RETURN", sends filtered water back to the pool. The middle right port, labeled "WASTE", sends water to an external drain hose.

Step 2

The other two ports control flow though the filter. This picture shows the valve as it is connected to the inside piping of the filter. At the bottom of the valve, a pipe port connects to the collection tubes (laterals) on the bottom of the filter. The area around the pipe on the bottom side of the valve directs water to the top of the filter. This picture shows water flow for a "FILTER" setting. Water will flow in the opposite direction with a "BACKWASH" setting. The next series of steps explains how each of the valve setting directs water though these ports. CAUTION. When selecting a valve setting, make sure that the pump has been TURNED OFF and always depress the handle before turning.

Step 3

FILTER. This is the normal setting for filtering your pool water and for regular vacuuming. Water from the pool is pumped into the "PUMP" port to the top of the filter. Contaminates are removed as the water makes it way to the bottom to be pushed back up through a central pipe to the "RETURN" port and back to the pool.

Step 4

BACKWASH. After a period of time, the contaminates start to clog the sand to the point where water flow is significantly diminished and the pressure gauge rises 8 to 10 psi above normal operation readings. To clean out the contaminates, you have to backwash the sand. In the backwash setting water flow is reversed though the filter. Water comes from the "PUMP" port down the filter through the central pipe, then back up through the sand to flow out the top exit of the filter and out the "WASTE" port to an external drain. As the water flows up though the sand, the sand is lifted about 7 inches above its normal height releasing the trapped contaminates to be purged out in the waste water.

Step 5

RINSE. After backwashing, the sand is loose and needs to be reset. Also any dirty water from backwashing has to be rinsed out of the filter to waste to prevent it from returning to the pool. With the valve in rinse mode, water is directed from the "PUMP" port to the top of the tank to compress the sand. As in the filter setting, the water flows down though the sand and back up though the central pipe but instead of going out the "RETURN" port to the pool, the water is diverted out the "WASTE" port.

Step 6

WASTE. This setting is used to bypass the filter when you want to vacuum the pool after an algae treatment or to lower the pool level. The water enters the valve though the "PUMP" port and exits though the "WASTE" port.

Step 7

CLOSED. This setting is used for shutting off all flow to the filter and pool. Water flow is stopped at the "PUMP" port.

Step 8

RECIRCULATE. This setting is used to bypass the filter during certain pool cleanups and chemical treatments when you don't want the water contaminating the sand. Water enters the valve through the "PUMP" port and exits back to the pool through the "RETURN" port.

Step 9

WINTER. Use this setting when you are closing down the pool for the winter. This will allow water to drain from the valve.


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Inyopools  Posted: 10/06/2014 13:21 PM  Inyo Product Specialist

MPV Drawing - I would suggest contacting the valve manufacturer. They should have a picture of your valve label in their system that they would send to you.

Anonymous  Posted: 10/05/2014 18:58 PM 

where can I get a drawing of the positions of the multiport valve.

Inyopools  Posted: 09/27/2014 11:46 AM  Inyo Product Specialist

Low pressure - A clogged impeller is a good place to start. See our guide on "How To Clean Out a Pool Pump Impeller". If that's not the problem, try our guide on "How To Determine the Cause of Low Water Flow".

Anonymous  Posted: 09/26/2014 18:21 PM 

Installed a new multi port valve and sand. Now cant get the pressure above five. Pressure good at intake but low on all discharge settings cant find any problem. Could the impeller be clogged

Inyopools  Posted: 07/24/2014 9:57 AM  Inyo Product Specialist

TC - When your gauge reads 0 while your pump is running, I would assume that your pump has lost prime - the strainer basket has no or little water in it. That would indicate that you have a suction side leak in the connections of the pipes coming from the pool to your pump. Try soaping up the suction line connections to see if bubbles get sucked in to a leak. I would concentrate on the line that you shut off to get the system working. The leakage around the chlorinator is on the discharge side of the pump, and though annoying, would not cause your system to lose prime.

TC  Posted: 07/22/2014 9:39 AM 

My filter has been giving me problems. Its a hayward s244t sand filter I believe. I just bought the house and trying to figure out how to get everything running. I dont think the system is very old. I finally played around with it long enough yesterday after 3 pool guys came out and couldn't fix the issue. Sometimes it filters and sometimes it wont. Sometimes the guage won't leave off of 0 and right now its at 10 and the filter is running. I was finally able to backwash and rinse it yesterday. Im afraid that if I turn it off it wont work again. I have the right valve turned off (not sure where it leads to) and it seems to be working fine vs both valves open leading to the skimmer by the pump. Please advise on what could be the issue. Even though its working there has to be something faulty. There is also some leakage around the inline chlorinator.

Inyopools  Posted: 07/11/2014 11:34 AM  Inyo Product Specialist

low pressure - Here's a link to our guide on "How To Correct Low Water Pressure in Your Pool System". It has suggestions on how to resolve common low pressure issues. If you haven't changes your filter sand in the last 5-7 years, that also may be a problem. Here's our guide on "How To Change Sand In a Sand Filter".

Anonymous  Posted: 07/10/2014 18:59 PM 

I have low pressure in the filter position. Backwash several times no change in operation. Im not sure if its the multi-port valve or the sand can you please advise. The filter is a haywood SP 714.

Inyopools  Posted: 06/28/2014 10:19 AM  Inyo Product Specialist

Phil - Assuming the filter is all installed, the start-up sequence is to first set your multiport valve to backwash and run it for 2-3 minutes, then set the valve to rinse and run for 30 seconds, then set the valve to filter for regular operation. Remember to shut off the pump each time your change filter modes, so you don't damage your filter gasket. If you have a lot of debris in your pool, get as much of that out of the pool with a hand skimmer before you run the pump, so you don't clog up the filter.

Phil  Posted: 06/27/2014 1:51 AM 

Great web site! I am installing a new above ground pool and am using a multiport filter, what do I need to do when I switch it on for the first time? Thanks

Inyopools  Posted: 06/17/2014 10:49 AM  Inyo Product Specialist

chronoallison - Sounds like your spider gasket in your multiport valve is damaged. See our guide on "How to Replace a Spider Gasket on a Multiport Valve". Remember to always turn off the pump before changing the valve setting.

chronoallusion  Posted: 06/17/2014 9:00 AM 

I have it set properly and it is not on waste but the waste water hose is spewing water out faster than it can be filled?

Inyopools  Posted: 06/11/2014 10:15 AM  Inyo Product Specialist

Barb E - You can turn the handle on the valve either way but be sure to sure the pump is off before you rotate the handle or you can damage the spider gasket. It sounds like the valve's spider gasket may be damaged. Check the gasket and replace it if required.

Barb E  Posted: 06/10/2014 22:51 PM 

Does it matter which way you turn the multiport valve? should you always turn it clockwise? I am having a problem with water flowing out when the valve is in filter setting. At first I thought the pool had a leak until I realized there was water flowing out the blue discharge hose when the valve was turned to filter.

Inyopools  Posted: 06/09/2014 13:22 PM  Inyo Product Specialist

Sandy pool - Check to make sure that your valve's spider gasket is not torn and letting dirty water back into the filter cycle. Also, if you just changed your sand, the very fine sand may be getting through the filter. Vacuum this sand off the bottom of the pool and dump it out the waste line.

Sandy pool  Posted: 06/08/2014 21:04 PM 

After I clean my pool to waste, then backwash, rinse and finally filter sand keeps flowing back into the pool. What do I do?

Inyopools  Posted: 05/31/2014 10:41 AM  Inyo Product Specialist

Suzanne - If you are going to a cartridge filter, you can get rid of the multiport valve. They are only used with DE and sand filters and have no other application.

Suzanne  Posted: 05/29/2014 19:06 PM 

I have an old Hayward DE filter and old speck pump. Since the pump has a hairline crack I will be replacing it and have decided to get rid of the DE filter too...I want to go with a cartridge filter. I am trying to get the right filter/pump and am wondering If I should also get rid of the multiport since I wont actually use it or can it be useful in another way to me?

boogerdave  Posted: 05/22/2014 14:05 PM 

The whole valve assembly is new . . right out of the box. I have checked both the gasket (glued in) and also removed the spring to try and stretch it a little. I guess I will order a new spring and give that a shot. When I switch from low to high speed, I can see the selector handle lift a bit . .

Inyopools  Posted: 05/22/2014 9:53 AM  Inyo Product Specialist

boogerdave - Sounds like water is still getting past your spider gasket. Check that gasket again. Be sure to turn off the pump every time you change valve settings or you will blow the gasket. Also your spring may look good but be weak. Consider changing the spring. See our guide on "How To Replace a Pool Multiport Valve Spring" for more information.

boogerdave  Posted: 05/21/2014 11:32 AM 

I just replaced the waterway multiport valve assembly on my sand filter and now when the pump is on high the water leaks (runs) out of the waste (backwash) port. I have checked the gasket, spring etc and still tends to compress the spring on the selector handle . . then, the leak starts. Funny part is, when the pump hasnt been running for a while, it wont leak at first but within about 5 minutes it continually starts and gets worse. Doesnt do it on low pump speed

Inyopools  Posted: 05/09/2014 16:47 PM  Inyo Product Specialist

Pool Start up - Don't use "filter" until most of your winter debris is out of your pool. It will clog up your filter. If you have a lot of heavy debris in your pool, use a net to screen out the big pieces. Then set your multiport valve to "Waste" until most of the smaller debris is out. Then set your MPV to "filter". When you are in "waste" mode, push the debris on the bottom to the main drain to speed up the process.

Anonymous  Posted: 05/09/2014 9:02 AM 

What setting should the vari flo valve be on when re starting the pump after the winter? Should I use the waste setting for the first time I vacuum or can I run it through the filter? This is my first time starting the pool on my own so I am confused.

Inyopools  Posted: 04/25/2014 9:19 AM  Inyo Product Specialist

Vannessab623 - Pulling the cleaner should not have had an effect on the filter. Check that you still have the filter connected to the pump properly then check to see if you have a damaged multiport spider gasket. See our guide on "How to Replace a Spider Gasket on a Multiport Valve" for more information.

Vanessab623  Posted: 04/22/2014 20:39 PM 

Hi, I have an ingrounf pool with a Hayward sand filter with the multi valve. When we bought the house it had an automatic cleaner. I pulled the cleaner out because it needs to be repaired but now I can't get my filter to work. All hoses are removed and I tried the filter and recirculation setting and neither worked. Can you help?

Inyopools  Posted: 04/15/2014 18:24 PM  Inyo Product Specialist

Eric - If you just opened your pool and the water was full of debris, you may have clogged your filter badly. You may have to backwash it several times to get the debris out of the sand. If the water still has a lot of debris, net it out and purge as much of it out through the waste line as you can before passing the water through your filter.

Eric  Posted: 04/15/2014 11:36 AM 

Hi there, I have a Jandy sand filter on a 25k gallon pool with a 1.5hp hayward pump. Unfortunately I cannot give a lot of details on the filter as I bought the house w/the pool and the label on the filter is very worn, but I am able to see Jandy and their logo. But the flow of water back to the pool decreases dramatically after about a couple hours of running after it's been backwashed. I just changed the sand last summer. I can backwash and it seems to have full pressure again, but then after a couple of hours loses most pressure coming back to the pool. Is that a bad multiport valve? It's a waterco multiport valve. I've replaced the center pipe O-ring as well and the main o-ring between the valve and filter is in good shape. Thanks for any direction you can give me.

Inyopools  Posted: 04/11/2014 0:10 AM  Inyo Product Specialist

BZ - Check your multiport valve spider gasket. It may have a tear in it.

BZ  Posted: 04/08/2014 21:33 PM 

I have a strange scenario. I have a Hayward Sand filter 244t. When the pump is running, all of the settings on the multiport work fine except "waste". Filter, recirculate, and backwash work fine. When set on waste however, the water discharges, but it is pulsating. There is a smooth flow of water in backwash mode, but waste pulsates badly. Any thoughts?

Inyopools  Posted: 12/06/2013 10:17 AM  Inyo Product Specialist

bill - Multiport valves may vary with manufacturers, but according to the Hayward rep, the ports on their Multiport valves are set up differently. For the DE MPVs the top port is "out" and the bottom port is "in". For Sand MPVs the top port is "in" and the bottom port is "out".

bill  Posted: 12/04/2013 10:18 AM 

What happens if you install a multiport valve that says use on de filter on a sand filter? Do they operate differently? I see some that you can use in both systems and some that say use only on de filters.

Inyopools  Posted: 10/27/2013 9:44 AM  Inyo Product Specialist

Henry - It depends on where your leak is. Check the spider gasket. See "How to Replace a Spider Gasket on a Multiport Valve". Check the O-ring between the multiport valve and the filter body. And check the O-rings around the stem of the valve that the handle attaches to. See "How To Replace a Pool Multiport Valve Spring". Note, not all valves have the stem O-rings.

Henry  Posted: 10/20/2013 19:29 PM 

What is the problem if water starts coming out of the multiport valve? The problem settles down after a backwash and cleaning out the DE powder but starts up again after awhile. Does the valve have a rubber seal that needs replacing? Thanks for your help.

Inyopools  Posted: 10/14/2013 10:04 AM  Inyo Product Specialist

kenny - If your pool has a lot of debris in it, set you multiport valve to "Waste" so you don't clog up your filter. When the pool is reasonably clean, you can leave your valve at "Filter" when vacuuming.

kenny  Posted: 10/06/2013 18:46 PM 

we just moved into a house with an in ground pool. What setting should the filter be on before I vacuumed the pool pls.

Inyopools  Posted: 10/03/2013 14:11 PM  Inyo Product Specialist

Spooner - Sounds like you have a leak. Try shutting down one of your suction lines at a time for a day and see if you stop losing a 1" of water for that day, then open that line up and shut down a different one. If that doesn't isolate your leak, try the same procedure on the other side [pressure] of the pump. As for the sand in your pool, see our guide on "How To Reduce Sand in Your Pool"

Spooner  Posted: 10/02/2013 21:47 PM 

I have moved into a house that has a pool and it is the first time that I have had one. The pool has a Hayward sand filter with six (6) settings on the multiport valve, for some reason looses about 6"-9" a week of water. IS this normal? I understand there is evaporation, but that seems a little excessive for evaporation. Also, when it sends water back to the pool there is, what seems like to me, a bunch of sand back into the pool with the water. Is this normal too?

Inyopools  Posted: 09/23/2013 12:28 PM  Inyo Product Specialist

multiport valve - It sounded like your valve handle or multiport top assembly was mounted 180 degrees from its correct position. That often accounts for "filter" acting like "backwash" and vice versa. But, if that was the problem, you should have corrected it with the new multiport. I don't know where the hoses are connected now, but the hose from the pump has to be connected to the top port, usually labeled "PUMP". "RETURN" port goes back to the pool and "WASTE" goes out the waste line. Make sure you turn the pump off each time you change the valve setting or you will blow the new valve gasket and water will go out the wrong ports.

Anonymous  Posted: 09/22/2013 20:56 PM 

I recently moved into a house with a pool and this was my first year. I'm having serious filter issues. At the start of the season I noticed that whenever I put my filter into the filter position water poured out of the backwash line. When I put it on backwash, the water ran back into the pool, but so did the dirt. I looked online and saw that it might be a bad gasket, so I replaced the whole multi-port. It still does the same thing. I switched the two lines thinking I put them on wrong, but it leaks on every setting. Can anyone help? I'm so frustrated and I don't know what to do. :(

Inyopools  Posted: 08/20/2013 11:33 AM  Inyo Product Specialist

Ken - I think you are fighting gravity. The pump on an above ground pool is gravity fed. Your multiport valve works fine in filter mode because there's nowhere for the water to go when the pump is off. When you are in backwash mode with the pump off, you have an open line to the waste port and gravity will pull the water from the higher pool out the waste line. Most AG pools have a shut off valve between the pool outlet and the pump that can stop to flow of water in cases like this. Or make sure the multiport valve is in filter mode when you shut off the motor.