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: 07/09/2017 16:21 PM  Inyo Product Specialist

Anonymous (valve spring) - I'm not sure I understand your problem. The spring should be compressed and held in place with a pin before you bolt the key assembly back onto the valve body. See our guide on "How To Replace a Pool Multiport Valve Spring".

Anonymous  Posted: 07/07/2017 7:20 AM 

I have a hayward S02465 sand filter which is leaking from the valve. I have removed the top to check the seal (O ring) but I can't bolt the cover on again. The spring is very strong and even with all my weight on it I can't get the bolts to line up. What do I do?

Inyopools  Posted: 06/30/2017 9:19 AM  Inyo Product Specialist

Cdm - New sand that you just put in your filter often has very fine sand mixed in it that gets thru the laterals when you are first starting up. This problem should go away. Also, check that you have the required free space between the top of the sand and the top of the tank. Check your user's manual for the height of the space.

Cdm  Posted: 06/27/2017 22:31 PM 

I have the pentair sand dollar filter. It is brand new. I notice sand entering my pool. The laterals are fine. What else could cause sand entering the pool?

Inyopools  Posted: 06/04/2017 22:51 PM  Inyo Product Specialist

Anonymous (MPV modes) - Did you pull the top off of your MPV recently? If so, could you have rotated the top 180 degrees so that the Backwash and Filter modes were swapped? Most MPVs are slotted so you can't misalign them but not all. Or did you recently buy a new MPV and select a DE MPV instead of a sand MPV. Some are designed differently depending on the manufacturer. See or guide on "How a Hayward Sand Multiport Valve Differs from a DE Multiport Valve".

Anonymous  Posted: 06/03/2017 16:41 PM 

My sand pump is hooked up correctly but when in the filter position it backwashes and in the backwash position it filters and i have changed and checked every hose several times and the pump is only 2 years old also the pressure gage shows normal

Inyopools  Posted: 05/25/2017 22:34 PM  Inyo Product Specialist

tkehoe - If you had a weak spring, it might contribute to your problem, but is I understand you correctly, you have had this problem with two new MPVs and one key assembly unit with a glued in spider gasket. At 10 psi, pressure is not a problem. Are you shutting off the pump before you rotate the handle? Is the leak always into the waste line? It sounds like a faulty spider gasket problem. Take the MPV apart to see if the gasket is damaged.

Inyopools  Posted: 05/24/2017 11:01 AM  Inyo Product Specialist

Rover100 - Typically, backwashing a DE filter removes 80% of the DE powder, so you would only want to refill with 80% of the install load. If you add the full amount, you may overcoat the grids to a point where they would restrict the water flow creating high pressure and low water flow.

tkehoe  Posted: 05/23/2017 20:35 PM 

I have a hayward multiport valve brand new install everything including pool and water. I added 150 lbs of sand per manual. I have a leak coming from the waste. I have been in contact with hayward and they sent out a new "channel" with gasket which was installed and only made the leak worse. They than sent out a whole new unit and yet the problem still persists. The pressure is reading at just 10 psi. Is it possible that the pressure is pushing up on the spring for the slow leak? I was told anything over 15 psi than it's time to backwash. Does high pressure push on the spring and open the valve? How would you control the intake and out take of water?

Rover100  Posted: 05/23/2017 13:09 PM 

On a DE filter using the multiport valve does backwash remove the DE from the filter cartridges? and if so, how much of it is removed (50%-90%, ?) So when you RINSE and then go back to FILTER you need to add same amount of DE or slightly less?

Inyopools  Posted: 03/31/2017 11:13 AM  Inyo Product Specialist

Anonymous (Multiport Valve) - Check the spider gasket in your MPV to see if it is damaged. See our guide on "How to Replace a Spider Gasket on a Multiport Valve". Then check that the Spring and Washers on the MPV handle for damage. See our guide on "How To Replace a Pool Multiport Valve Spring".

Anonymous  Posted: 03/28/2017 18:54 PM 

I do all the right things with the pool . However I have a lot of trouble pushing the lever around . It is so stiff . Is it alright to spray the lever with WD40 . I have done this and it makes it a bit easier . Can you replace this part of the pool system . Regards June Jennison .

Inyopools  Posted: 02/27/2017 14:44 PM  Inyo Product Specialist

Haypool - I would check the spider gasket in your multiport valve first. Even if you can't see leaks from the valve, you have a damaged gasket that opens up paths in the MPV that shouldn't be opened. Then I would look for suction leaks before the pump that could be sucking air into the system and causing pressure buildup. When the system is shut off, this buildup could reverse water flow through the system pushing water back into the pool. This could cause your system to drain and require additional priming on startup.

Haypool  Posted: 02/26/2017 16:43 PM 

I have a SP071620T multiport which works in all positions and no external leaks of water on pump or filter (anywhere visible). When the timer shuts off the pump though, something is leaking air back through the system which leaves the pump needing to pull water back from the pool every time the timer starts things up again. If I move the multiport selector to rinse, it held much more water than before but still slowly leaked air in. Where could the air be coming from and what's causing it? The waste port has a separate inline close valve after the multiport waste exit so shouldn't be coming from there.

Inyopools  Posted: 02/14/2017 11:23 AM  Inyo Product Specialist

Multiport Valve does not turn - I'd check two areas. The white plastic bearing washer underneath the handle sometimes cracks and interferes with the handle's rotation. See our guide on "How To Replace a Pool Multiport Valve Spring" for the location of this washer. Also, check that the spring is not broken or weak. The other area to check is the spider gasket. See our guide on "How to Replace a Spider Gasket on a Multiport Valve" for the location of this gasket. If the gasket is damaged, it can interfere with the rotation of the handle.

Multiport Valve does not turn  Posted: 02/13/2017 22:04 PM 


Thanks for your video, my Multiport Valve can be turned at all. It's pushed but it's stuck somewhere that I can turn it (i.e from filter to backwash?

Any suggestion?

Inyopools  Posted: 12/12/2016 11:15 AM  Inyo Product Specialist

cklapd - Generally the top of the valve assembly is keyed preventing you from rotating the top 180 degrees. If it is not keyed, you could try rotating the top. I'm not sure how the other settings would line up, but it's worth a try. You label of course will be off.

cklapd  Posted: 12/07/2016 22:59 PM 

I just bought a pentair MPV for DE FNS plus filter. My plumbing config does not match the MPV Waste (on the left side) and the Return (on the right). I want to switch those. Can I just open the unit and rotate the guts 180 degrees?

Inyopools  Posted: 11/29/2016 10:42 AM  Inyo Product Specialist

Mike - Do you know the make of the valve or what filter it is attached to?
And what are the other valve settings? "Drain" is probably "Waste". The others don't seem to correlate.

Mike  Posted: 11/27/2016 13:16 PM 

On my valve I have test, whirlpool and drain. Do these correspond to closed, recirculate and waste?

Inyopools  Posted: 11/27/2016 10:04 AM  Inyo Product Specialist

multiport repair - Generally, a leaking multiport valve is caused by a damaged spider gasket inside the valve. A spider gasket costs around $20 by itself. If it comes pre-glued to the diffuser, it can cost around $45 to replace. See our guide on "How to Replace a Spider Gasket on a Multiport Valve" for more information.

Anonymous  Posted: 11/25/2016 15:23 PM 

how expensive is it to repair a leaking multiport?

Inyopools  Posted: 09/28/2016 11:19 AM  Inyo Product Specialist

open backwash valve - Not sure what you mean by "left my backwash valve open". If you were in backwash mode with the pump on for 24 hours, you must have dumped half your pool water. I'll assume your pump was off and you just had your valve set on backwash for 24 hours. That should not have affected your pool. Just set it back to filter (with the pump off) and wait for the next filter cycle.

Anonymous  Posted: 09/27/2016 11:47 AM 

Hi. I accidentally left my backwash valve open for the last 24 hrs and the pool is cloudy. Checked the water and chlorine and ph are fine. Should I just leave it on the timed cycle or continuous or off?


Inyopools  Posted: 09/13/2016 22:56 PM  Inyo Product Specialist

Larry - See our guide on "How To Backwash a Pool Filter With No Valve Label". It should help you determine what your operational settings are.

Larry  Posted: 09/12/2016 14:25 PM 

My daughter just bought a house with an old pool. The equipment runs fine but as we approach closing season I have a problem. The mpv on the old filter has no setting labels. How can I find out the setting positions for backwash, waste, close, winter and rinse? The filter brand is a Citadel Central model P20. Can anybody help me?

Inyopools  Posted: 09/10/2016 16:14 PM  Inyo Product Specialist

Beatle - You should not have to add a sealant between the valve and the tank. There should be an O-ring at that junction. Take the o-ring off and check for cracks in the o-ring, or the top of the tank. Check also for cracks in the flange of the valve that connects to the tank. If your leak in around the handle, check the two o-rings around the shaft.

Beatle  Posted: 09/05/2016 20:34 PM 

Hi, I have a sta-rite 2" multi port valve and I just replaced the spider gasket. However, when I reinstalled the valve cover, it leaks. I did lubricate the o-ring, but that didn't seem to help. Do you recommend any sort of sealant between the cover and the base? Thank you.

Inyopools  Posted: 07/19/2016 19:16 PM  Inyo Product Specialist

loosing water - Recheck the spider gasket. That's the source of most water flow problems. Remember to turn off the pump any time your move the MPV handle. Also, check if the valve spring under the handle is weak or broken. A bad spring will prevent the gasket from sealing.

Anonymous  Posted: 07/17/2016 23:58 PM 

Hi - wondering if someone can help?

When in Filter mode my pool is draining quite quickly - that is I'm loosing water down the waste. I have cleaned the top of the multi-port valve to make sure the lever isn't stuck in a non filter position and checked the spider valve and it looks fine. Any ideas what else I can do? cheers. It is an Astral Pools (Hurlcon) glass media filter RX series.

Inyopools  Posted: 07/05/2016 9:46 AM  Inyo Product Specialist

Josh - This one has me stumped. If you were able to install the MPV 180 degrees off, the other modes would not work. What happens when you have the valve in Closed mode. That's the setting for no flow. See our guide on "How a Multiport Valve Operates II". It explains how the valve works inside. Also looks at Steps 25 and 28 in "How To Replace the Sand in a Pentair Triton 2 Side Valve Sand Filter". Do your valve positions look like the ones in this picture? Some manufacturers have different designs for sand and DE MPV. Lastly, check your spider gasket in the MPV to make sure it's not damaged.

Josh  Posted: 07/01/2016 1:47 AM 

I replaced an old MPV on a Pentair Triton side mount filter and after doing so i noticed when i moved it to recirc nothing is return of water to the pool and no suction at the skimmer. Backwash, waste, rinse, and filter all appear to be working properly...could i have installed the the new MPV incorrectly? ie, spun 180 degrees etc.

Inyopools  Posted: 06/27/2016 13:36 PM  Inyo Product Specialist

No return on MPV - The Filter and Recirculate setting are the only ones that use the Return port to the pool. Check that the port is not blocked. Then check that the spider gasket in the MPV is not damaged. See our guide on "How to Replace a Spider Gasket on a Multiport Valve". for more information. Also, check that you have the right MPV for your system. There is a difference between a DE MPT and a Sand MPV. See our guide on "How a Hayward Sand Multiport Valve Differs from a DE Multiport Valve".

Anonymous  Posted: 06/25/2016 17:24 PM 

Every mode of the filter works except for the filter and recirculate. Is is possible the valve is bad or just blocked?

Inyopools  Posted: 06/22/2016 10:03 AM  Inyo Product Specialist

Tricia - You have little choice. You will have to vacuum up the bottom algae out the waste port and add water. If your pool is balanced now, you should only have to add the cheaper basic chemicals to rebalance your pool.

Tricia  Posted: 06/22/2016 9:21 AM 

I tried twice to vacuum my inground pool. I watched 3 diff videos on how to do it and I did everything they said. I don't seem to be getting much suction. When I originally did it, it was just a normal job-- settled dirt mainly. Now I have combined chlorine so the chlorine attached to the dirt, which created a huge chemical imbalance and now I have what looks like algae clumps on the bottom of the pool. I went to my local pool store and had the water tested and spent about $100 to correct the water. should I vacuum on the waste setting to remove the clumps? I read on your site that would decrease the water level which concerns me because I will need to add water again and I just got the water balanced again. Please help. This is my first pool and I'm so lost!!!

Inyopools  Posted: 06/12/2016 11:27 AM  Inyo Product Specialist

Jack - RINSE and BACKWASH are the only settings that use the WASTE port. So it would appear that something is blocking the WASTE port either inside the Valve or in the plumbing going out from the WASTE port. Check the outside plumbing first since that is the easiest to access. Then take the top off of the valve (8 - screws) to see if something is blocking the WASTE post from the inside.

Jack  Posted: 06/09/2016 19:48 PM 

Just bought a new Hayward filter head for my sand filter and it won't backwash! Checked the sand in the tank and it's not solid and is actually very loose. Troubleshooting it it pulled the head off and checked its operation and all but the backwash and the rinse will not work. The pump works fine and it works in filter mode but again not backwash or rinse... What the heck?

Inyopools  Posted: 06/06/2016 11:26 AM  Inyo Product Specialist

HOTLAP - The pump should be turned on during the RINSE cycle. RINSE for 1-2 minutes. See our guide on "How To Backwash a Pool Sand Filter".

HOTLAP  Posted: 06/04/2016 14:29 PM 

Should I run the pump motor during the rinse cycle or just let the water naturally flow thru, also how long should I rinse?
Thank You