Swimming Pool Blog

Vacuuming to Waste: A How-To

How to Vacuum a Pool to Waste
by Mark Garcia August 26, 2014

How to Vacuum a Pool to Waste
how to vacuum to waste


Hello - just back from a long August vacation, and while away I received an email from a customer about their threadbare winter pool cover.

One drawback to the old mesh safety cover is that it lets in a lot of light and silt. Vacuuming in the spring is a large chore, especially since the DE filter was attached to a push-pull type of valve, with no option to 'vacuum to waste'.

Vacuuming to Waste essentially means that the pump pushes the water into the filter valve, which diverts it straight into the waste line, bypassing the filter sand, grids or cartridges.

There are different ways to vacuum a pool to waste, depending on which type of filter valve you have - a multiport valve or a push-pull (also called slide) valve, or even no filter valve at all.




  1. Fill the pool before beginning, and run the hose while vacuuming.
  2. Shut off pump and switch the multiport valve to the Drain to Waste Position.
  3. Vacuum as fast as possible, the water level can drop fast.
  4. Stop vacuuming when the skimmer begins to suck air, allow the pool to refill.
  5. Move the backwash hose frequently to avoid erosion and oversaturation.

Vacuuming to Waste: Why and When

Vacuuming to waste is helpful when there is a lot of debris in the pool, especially silty dirt, that clogs up the filter quickly, requiring you to stop vacuuming to backwash or clean the filter. When one vacuums to waste, the water never enters the filter tank, but is jettisoned out the waste port, and exits through the backwash hose or pipe.

Vacuuming to Waste: How and What

Multiport Valve: waste port on multiport valve

For multiport valves, those that have 6 settings, set the valve handle into the "Waste" or "Drain" position. Roll out the backwash hose if you have one, and begin vacuuming as fast as you can manage. Remember, the water level is dropping!

Push-Pull Valve:

Push pull valves use a piston with two disks, and have only two settings, Filter or Backwash. In the down position, the water is directed through the tank on Filter mode, returning to the pool after it exits the filter tank. In the up position, the water enters the waste line as it exits the filter. (Pac-Fab push-pull valves have a reverse operation, up for Filter, down for Backwash).

Since there is no "Drain" setting on a push pull valve, it would seem that there is no way to vacuum to waste on a filter with a slide valve - or is there? 

For DE filters, you can remove the grid assembly and reassemble the filter tank tightly, being sure that the clamp is properly positioned and very tight. Open the air bleeder and set the push pull in the backwash position. Adjust your skimmer and main drain valves for maximum suction through the skimmer, and voila! you can vacuum the pool to waste. If the push pull plunger falls down, into the filter position, use vice-grips or a small wrench to hold it in place. how to vacuum to waste with a push pull valve

For Sand filters using a push pull valve, you can't remove all of the sand. It would seem that there is no way to vacuum to waste a sand filter - or is there? 

There is a method, but it can be dangerous, so read carefully. Remove the plunger from the slide valve housing or body by loosening the large union nut, small bolts or nuts on the top, under the handle. Clean off any lubricant inside the valve body. Then insert a rubber expansion plug, usually a #11 or #12, down into the valve body. Tighten it fully with pliers, and don't stand over the plug, which would be dangerous if it blew out under pressure. Make sure the backwash hose is not kinked and open the filter air bleeder before starting pump. A straight sided pressure testing plug will hold stronger than a tapered winterizing expansion plug.

No Valve: 

Cartridge filters don't have a backwash valve at all, because you don't backwash them, you remove them and spray them off with a garden hose. It would seem that there is no way to vacuum to waste with a cartridge filter  - or is there? 

Option #1 is to remove the filter lid, and remove the cartridge, and replace the lid securely, fully tightening the clamp. Remove the drain plug and thread in a 1.5" hose adapter and backwash hose with a clamp. Run out the backwash hose to a storm drain or an area that won't erode or oversaturate. Don't flood the neighbors!

Option #2 is to install a 3-way valve in the pipe between the pump and filter. Pac-Fab 3-way valves are under $30, and the only other materials needed are a bit of pipe and some PVC glue and primer. Use a hacksaw to cut out about a 5 in. section of PVC pipe between the pump and filter, leaving 2-3" of clear pipe on both sides to connect the new valve. You may need help to pull apart the pump and filter slightly as you glue the new valve into place. Reset the valve lid to allow the water to flow straight through the valve for normal filtration, or take a hard 90° turn and go out port #3. Glue a short piece of pipe to the valve, and clamp a length of backwash hose to the pipe. Turn the valve whenever you want to vacuum to waste on a cartridge pool filter, or when you need to lower the water from too much rain.




Thanks for Reading! 
Mark Garcia