How does a multiport backwash valve work?

A multiport backwash valve has more features, but at the expense of flow. In this section we will describe the various features and settings of a multiport valve.

Multiport Valve Settings

Multiport valves have one major thing going in their favor – features. Here is a list of the settings on most multiport valves.

    • Filter – sends the water through the filter and back to the pool. This is the normal setting for any backwash valve.

Backwash – this sends the water backwards through the filter to flush out the dirt and DE inside the filter. It then directs this water out to the sanitary sewer by means of the backwash line.

Rinse – this sends the water through the filter, as in normal filter mode, but then instead of returning the water to the pool, it sends it to the backwash line. This is helpful with sand filters that need a rinse cycle.

Recirculate – this bypasses the filter and sends the water directly back to the pool. This is not advisable for long periods of time as it can send unfiltered water through the poolsweep or other places where it is not wanted.

Waste – this directs the water from the pump, directly to the waste line.

Closed – this does not allow water to flow any direction through the backwash valve. Do not try to run the filter with the valve in this position.

What is the best application for a multiport backwash valve?

    • If you have a sand filter, you really need the rinse setting that a multiport provides. This is because when you are backwashing a sand filter, you leave it in backwash mode for a lot longer than you do a DE filter (with a DE filter, you run several shorter backwash processes instead of a single long one).

In any event, whenever you are running in backwash mode, any dirt in the water becomes collected on the clean side of the filter, so that when you put the valve back in filter mode, that dirt is all sent back to the pool.

A multiport valve has a rinse setting which is basically a “filter to waste” setting that runs the water forward through the filter and then sends it to the waste line so that any debris that may have collected is not sent back to the pool. When backwashing with a multiport valve, you run the pump for a 15-30 seconds in the rinse setting before returning the valve to the filter setting.

What if I don’t like the flow reduction of a multiport valve?

    • You can get the same effect as “rinse” mode by putting a 3 way Jandy valve on the outlet of the filter and plumbing it in such a way that you can either send the water back to the pool or out to the sanitary sewer.

There are two potential dangers to doing this:

      1. Somebody could accidentally turn the valve and end up draining the pool. You can avoid this by keeping the equipment area secured and keeping unqualified people away from the equipment.


    1. Somebody could shut the valve off completely and cause a dangerous pressure buildup in the system. You can conceivably avoid this risk by setting the stops correctly on the 3 way Jandy valve so that the flow cannot be blocked without removing handle and jumping the stops.


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