Vacuuming to waste drains dirty water directly out of your pool instead of back through the filter

When you vacuum to waste, the pump pulls water from the pool floor, sends it through the vacuum hose, and expels it outside rather than cycling it back through the filter system. This method removes both debris and the water it sits in, which is useful when your pool water is very dirty, cloudy, or contaminated. The trade-off is that you lose water volume and have to refill afterward, but sometimes that's faster than trying to filter out heavy debris.

Most residential pools can switch to waste mode using a valve on the filter tank or a lever on the multiport valve. The exact location depends on your filter type, but the principle is the same: you're redirecting the water flow away from the filter media and straight out of the system.

Key Takeaways

  • Vacuuming to waste bypasses your filter entirely and expels water outside, so you'll need to refill the pool afterward.
  • Locate the waste valve or multiport valve on your filter tank—it's usually a lever or knob labeled "Waste" or "Drain".
  • Turn off the pump before switching the valve, then turn it back on once the valve is set to waste mode.
  • Watch the water level as you vacuum; stop when it drops below the skimmer intake to avoid air entering the system.
  • Switch the valve back to "Filter" mode and run the pump for a few minutes to clear the hose before you finish.

Locate your filter's waste valve or multiport valve

The valve that controls where water goes is mounted on top of or to the side of your filter tank. On a sand filter or cartridge filter, look for a round valve with a lever or handle sticking out—this is the multiport valve. On a DE filter, the multiport valve is also on top. The lever should have positions labeled "Filter," "Waste," "Recirculate," and sometimes "Backwash."

If your pool is older or uses a different setup, you may have a separate waste valve (a straightforward ball valve or gate valve) mounted on a pipe near the filter. This valve is either open or closed; you don't rotate it like a multiport lever. Check your pool's documentation or look at the filter tank itself—manufacturers often label the valve positions right on the housing.

Turn off the pump before switching the valve

Always stop the pump before you move the multiport valve or open a waste valve. Switching the valve while the pump is running can damage the valve, create a pressure spike, or cause water to spray out unexpectedly. Turn off the pump at the control panel or breaker, wait a few seconds for the system to depressurize, and then move the valve.

Once the valve is set to "Waste," turn the pump back on. You should hear water flowing and see it exiting through the waste line (usually a pipe or hose that runs away from the pool). If you don't see water flowing, check that the valve is fully in the waste position and that the pump is actually running.

Connect the vacuum hose and start vacuuming

Attach your vacuum head to the pole and connect the hose to the suction port on your skimmer or the dedicated vacuum port on the pool wall. Make sure the hose is fully seated so no air leaks in. Prime the hose by submerging it in the pool or running water through it until it's full—this removes air and helps the pump pull debris efficiently.

Lower the vacuum head to the pool floor and begin moving it slowly across the bottom, just as you would when vacuuming to filter. Work in overlapping passes so you don't miss spots. Because you're sending water outside, the pool level will drop noticeably. Keep an eye on the water level and stop vacuuming when it reaches the bottom of the skimmer opening—if the level drops below that, air will enter the suction line and the pump may lose prime.

Monitor water level and stop before it gets too low

The skimmer intake is your safety line. Water needs to cover that opening so the pump draws only water, not air. If air enters the system, the pump can cavitate (make a grinding or squealing noise) and lose its ability to pull water. Once you hear that sound or see the water level approaching the skimmer, stop vacuuming when ready.

If you have a lot of debris to remove and the water level drops before you finish, switch the valve back to "Filter" mode, turn on the pump, and let it run for a few minutes to refill the pool slightly from the hose. Then switch back to waste and continue. This takes a little longer but protects your pump.

Switch back to filter mode and clear the hose

Once you've finished vacuuming, turn off the pump, move the multiport valve back to "Filter" mode, and turn the pump on again. Let it run for two to three minutes. This clears any debris or air from the hose and lines before you disconnect everything. You may see some cloudy water return to the pool—that's normal.

Turn off the pump, disconnect the vacuum hose from the skimmer, and store it. If the waste line is still draining, turn off the pump and close the waste valve (if you have a separate one) or move the multiport valve fully to "Filter" to stop the flow.

Refill the pool to the proper level

Because you've drained water to waste, your pool level is now below where it should be. Use a garden hose to refill until the water reaches the middle of the skimmer opening—that's the target level for most residential pools. This usually takes 30 minutes to a few hours depending on how much water you removed and your water pressure.

While the pool refills, you can run the pump on filter mode to help circulate the water and begin filtering out any remaining fine particles. Once the level is correct, your pool is ready to use.

Frequently Asked Questions

Can I vacuum to waste if my pool doesn't have a multiport valve?

If you have a separate waste valve on a pipe, yes—open that valve and close the return line valve to send water outside. If you have neither, you cannot vacuum to waste; you'll need to vacuum to filter instead. Check your filter documentation or ask a pool service to identify what you have.

How long does it take to vacuum a pool to waste?

It depends on pool size and debris load, but expect 30 minutes to an hour for a typical residential pool. Vacuuming to waste is slower than vacuuming to filter because you're also removing water, so you have to stop and refill partway through if the level drops too far.

What if I hear a grinding noise while vacuuming to waste?

That's cavitation—the pump is pulling air instead of water. Stop when ready, turn off the pump, and check the water level. If it's below the skimmer, refill the pool and prime the hose again before continuing. If the level is fine, check that the hose is fully connected and not kinked.

Do I need to add chemicals after vacuuming to waste?

Yes, because you've removed a volume of water, you've also removed some of the chemicals dissolved in it. Once the pool is refilled, test the water and adjust chlorine, pH, and alkalinity as needed. The amount depends on how much water you drained.

Is it okay to vacuum to waste every week?

Occasional vacuuming to waste is fine, but doing it every week will waste a lot of water and chemicals. Use it when the pool is very dirty or the water is cloudy and won't clear through the filter. For routine maintenance, vacuum to filter instead.