Backwash Valves for Pool Filter Systems

A multiport (filter) valve routes water through different positions—like Filter, Backwash, Rinse, Waste, Recirculate, and Closed. It’s most commonly used with sand and DE filters to make backwashing and maintenance easier.

Match the valve to your filter brand/model and confirm whether you need a top-mount or side-mount valve. Then verify the port size (commonly 1.5" or 2") and connection type (threaded vs union). If you’re replacing an existing valve, the current valve part/model number is the fastest way to get an exact match.

A top-mount valve sits on top of the filter tank and is common on many sand filters. A side-mount valve mounts on the side of the tank and is often used on some sand and DE filters. The correct type depends on your filter’s design—choose the valve style that matches your existing filter and plumbing layout.

Valve size should match your filter/plumbing size. Many pools use 1.5" plumbing, while larger systems often use 2". If you’re unsure, check your existing valve label, measure your pipe/union size, or look up your filter model specifications before buying.

Often, yes. If you’re seeing water leaking to the waste line during normal filtering, weak backwash performance, or water bypassing internally, a worn spider gasket can be the culprit. If the valve body is cracked, badly worn, or the handle/rotor is failing, replacing the entire valve may be the better long-term fix.

The most common cause is a worn or damaged spider gasket inside the multiport valve, which allows water to leak between ports. A warped rotor, debris in the valve, or a worn seal can also cause bypass. If the valve is older or the internals are worn, replacing the valve assembly may be the easiest solution.

Use Filter for normal operation. When pressure rises or flow drops, switch to Backwash to flush debris out, then use Rinse briefly to resettle media before returning to Filter. Always turn the pump off before changing valve positions to protect the gasket and internal parts.

Many multiport valves are designed specifically for sand or DE filters (and some are model-specific). The safe approach is to match the valve to your exact filter model and mount style. Even if sizes look similar, internal routing can differ between filter types and brands.

Yes. If you share your filter brand/model (or a photo of the valve label), plus whether it’s top-mount or side-mount and your plumbing size, we can help you pick the right valve or the correct gasket/parts. Visit our Support page to contact a pool expert.