How a Multiport Valve Operates

Written by:  Danny Rhodehamel

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.

Tips & Warnings


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.

Comments (1 to 40 of 251)

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User: Inyopools

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.


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.

User: Inyopools

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.

User: Josh

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.

User: Inyopools

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".


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

User: Inyopools

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.

User: Tricia

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!!!

User: Inyopools

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.

User: Jack

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?

User: Inyopools

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".


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

User: Inyopools

Julie - You may have too much DE in the filter. Try pulling out the grid assembly and cleaning it. Check that the exit ports are not blocked. Only add about 80 % of the normal DE when you reinsert the grid assembly. See if that improves your water flow.

User: Inyopools

RPQ - This should not have damaged the valve. It just might have dumped some water where you might not have wanted it.

User: Inyopools

Dannymac – If you have a cartridge filter, it may be clogged up with oils and chemicals even though it looks clean. If the cartridge is 1-2 years old, you might consider replacing it. If you have a sand filter, backwash and rinse it 3-4 times to get any residue out of the sand. If the sand hasn’t been changed in 5 years, replace it.

User: Julie

WE have a Pentair multi port valve for a DE filter, when we backwash very letter water comes out, and a suction forms on the tube the water is suppose to come out of what might be the problem?

User: RPQ

When I started my pool this year I forgot to move from winter setting to filter. I caught it before the water went below the skimmers (probably a half hour). Will this affect my filter?

User: Dannymac

I am having trouble getting my pool clean, I suspected the filter was not filtering correctly, so I put food dye into the basket filter area, half the food dye come out the return during that same pump cycle, I had a look at the spider gasket, and to me it seemed fine, is there anything else I could look at? Thanks

User: Inyopools

Maureent - I'm not sure what you mean by tapping the multiport valve head off. I would recommend unscrewing the cover assembly - usually 8 screws. Then, lift the cover assembly off to expose the inside of the multiport valve and the spider gasket. Look at the gasket to see if it is damaged. Most multiport valve problems are due to a bad gasket. See our guide on "How to Replace a Spider Gasket on a Multiport Valve". Remember to turn off the pump each time you move the handle to a different mode.

User: Maureent

We have a new multivalve and sand filter but are having problems with water leaking out. We are assuming (by eliminating all other possibilities)that we are getting grit stuck in the multivalve. However we cannot get the multivalve head off. We understood this should only be hand tight but even with gentle tapping it just won't budge. Any ideas please?

User: Inyopools

Jose - When you replaced the handle, you may have set it on 180 degrees from where it should be. See our guide on "How To Replace a Pool Multiport Valve Handle", Step 9.

User: Jose

Ok... I have an issue. I set it to filter or any other setting for that matter and my pool drains as if it were on waste or back wash. It also pulls all the water out of skimmers completely. Ice replaced web and handle. What could it be

User: Inyopools

Emy - I am a little confused about your question, but if you are trying to lower the level of water in your pool, you would want to rotate your multiport valve to the "WASTE" position. Make sure you have a hose attached to the "waste" port to take the water away from the pump.

User: Emy

I have a question I want to know the pipe should be on or off because there are three pipes when I lower the level of the water

User: Inyopools

Terry K - I would recommend buying a vacuum head that attaches to your scrub brush pole and suction cleaner hose. Then manually suction off the white powder with the multiport valve in WASTE mode to keep the powder from going into the filter. You will have to add fresh water when you are done. Here is the link to "vacuum heads".

User: Terry K.

I removed my rhino pool cover today and there was a lot of white DE looking waste sitting on the bottom of our pool. The pool has been covered for the last 3 months.
Question? What's the easiest way to remove the white sediment from the bottom of our pool with or without filter utilization?
When I brush the pool, it cloudy ups the pool water.


User: Inyopools

wrong MPV - Unfortunately, in many cases, a manufacturer will design the DE MPV much differently than a sand MPV. See our guide on "How a Hayward Sand Multiport Valve Differs from a DE Multiport Valve". If this is your case, the only solution is to replace your current DE MPV with a sand MPV. Not all MPVs are different. Check with your manufacturer before buying another one.


We installed a de valve instead ofone for a sand pump. How do we correct this?

User: Inyopools

motor ran dry - If your system lost prime and your pump ran without water for a period of time, you may have damaged your motor. Without water the pump will run too hot and some of the gaskets and shaft seal may have failed and sprayed water on the motor winding. The motor overload protected may have turned your pump off. Fill your pool and try priming your pump. If it runs, watch for sprays around the pump gaskets and the shaft seal. If you see sprays, turn the pump off and replace all your motor gaskets and seals.


I have a question. I left my filter on waste and it rain like that all day. It drained the pool about 2 foot below the skimmer. I am filling back up now. I just wanted to know if I have have messed up my pump or the motor. Please help

User: wolf380

I just purchased a Pentair (was American Multiportvalve) 6 bolt and it is the correct one, however I did not know the O-Ring gasket was not a part of the valve. so now I need a gasket, O-ring and I can not locate it on your web page.

User: Inyopools

Bueno - Not always. It depends on the manufacturer. See our guide on "How a Hayward Sand Multiport Valve Differs from a DE Multiport Valve".

User: Bueno

Can a mpv for a sand filter be used on a d.e. filter?

User: Inyopools

FOMBELLBOB - It is possible on some multiport valves to reinstall the rotor 180 degrees out of position, so the modes don't operate properly. See our guide on "How To Replace a Pool Multiport Valve Handle" for an example of how this could happen. If this isn't the problem, you might trying cleaning the grids again to clean out the excessive dirt you filtered out of the pool. Also check the breather tube that goes from the bottom of the filter tank to the top. Make sure it isn't clogged and that the screen at the top of the tube is clear.


I have a nautilus ns36 de filter and a Pentair 1 1/2" multiport valve. we had a bad storm that left a lot of dirt in my pool.After filtering the pool is clean but don't have the sparkle it had before the rain. when I turn off the pool now I get de flowing back in from the suction ive replaced all of the rubber internal in the filter and multi valve and still I get de flowing back in the suction my pool is 24 yrs old and I never had this happen I also replaced the gridS in the filter 2 yrs not sure what is going on.please any suggestion. I was wondering if the rotor was put back in the valve the wrong way and letting a flow go back in the suction when shut off.ALSO I HEAR A GIRGLE SOUND FROM THE FILTER WHEN THE DE IS FLOWING BACK INTO THE POOL.

User: Inyopools

recirculate - No, the pool would not drain. In recirculate mode the filter is bypassed so you have a straighter line between the pool to pump ports and the pool return ports. Water may move a little when the pump is shut off but it would go back into the pool.


If I set my filter to recirculate and the filter timer shuts off the system will it drain the pool?

User: Inyopools

backwash failure - Check your spider gasket to make sure it is not damaged. Remember to shut your pump off when you move the MPV handle to switch modes, and always push the handle all the way down when you move it. See our guide on "How to Replace a Spider Gasket on a Multiport Valve" for more information.

User: Inyopools

Stan - The MPV is part of the DE filter. If you are suggesting leaving the DE filter in place and placing a new cartridge filter next to it, I don't see why I think you are saying will not work. With the MPV in "Waste" mode, you would be bypassing the DE filter and going straight into the new cartridge filter. Kind of jerry rigged but I don't see why it wouldn't work.


Replaced the multiport valve unit, but now the water doesn't leave the pool during backwash cycle. After running I got the backwash cycle for a few minutes,a suction forms in the incoming line forcing a collapse in the return line

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Tips & Warnings

Continue backwashing until the water shows clear in the sight glass on the side of the valve.

Don't backwash excessively. Contaminates in the sand actually help the filter work more effectively - to a point. Monitor your pressure gauge for an 8-10 psi rise.

Never move the valve handle when the pump is on.

Don't vacuum your pool in backwash mode. You may clog the collection pipes (laterals) at the bottom of the filter.

Please Note:

Inyo Pool Products is not responsible for any injury or damaged equipment
while using our guides. Using our guides is doing so at your own risk.
These guides are suggested use of your pool or spa equipment and may vary
depending on which product you are using.