Last Updated: May 28, 2022

How To Vacuum Swimming Pool To Waste

Written By: Pool Care Guide

If your swimming pool has a feature that allows it to run the filter in a 'waste' mode, you'd be wise to understand this function. Knowing how to vacuum to waste can be a huge ace up your sleeve when the bottom of the pool gets dirty, coated with algae, or at the opening of the pool season. 

There are quite a few different ways to use the waste valve. Let's look at them all, especially how you can vacuum to waste and why it makes sense. 

Why Vacuum to Waste?

Your pool's filter system starts by sucking the water into a drain or skimmer when it's in regular operation. The pump is the heart of the circulation of the water, drawing water from the pool, through the pipes, and into the filter tank. 

Sometimes, having a waste setting is a convenient way to remove excess water from the pool, say after a big rainstorm. 

It's even more advantageous when you want to vacuum the bottom of the pool and remove all the accumulated sand, silt, algae, and debris without sending the water through the filter and dirtying its internal media. 

The best example of this is when you first open a pool for swimming season. You're likely to find a layer of sediment and sludge on the bottom. If you use your vacuum to suck it up while the filter is in its standard-setting, all of that nastiness will enter the tank, overwhelm the filter, and spray back into the pool through the return plumbing. 

It's far better to set your valve to waste, bypass the filter tank, and send the dirty water to a remote part of your property or a nearby drain. 

Vacuuming to waste is also helpful in some other situations:

  • During an algae bloom (don't forget to consider an algaecide)
  • When the pool is dirty after a big storm
  • After using a flocculant to settle particles to the pool bottom

Using The Waste Setting 

After the water is cleaned and processed by your filter, it passes through return pipes that bring it back to the pool. If you have a multiport valve, a fairly standard feature, you'll see that there is a setting for filter, backwash, rinse, closed, and waste. This multiport valve allows you to manipulate the water flow through the system easily. 

Switch it to backwash, and you'll reverse the flow of water from the pool to wash the sand or grids inside the tank forcefully and then send the dirty water to waste. Use the rinse to clean the pool's side of the filter by sending the water in the same direction as usual, but right across the media and then to waste.

The closed setting helps prevent the water from leaving the pool, like during periods where you're working on the plumbing. 

By changing the position of the multiport to waste, you bypass the filter tank, pumping the water to an outlet pipe that removes it from the system. Bypassing the filter tank can spare it from a dirty vacuum. 

Sometimes, the multiport may have a setting to recirculate the water. This position also bypasses the tank but sends the water back to the pool, not out to waste. It's useful when you want to add chemicals to the pool that shouldn't enter the filter. 

Other Types of Valves: Tricks

Not every pool has the advantage of a multiport. Instead, you might have a push-pull valve that allows you to switch between normal filter mode and a backwash setting for cleaning the filter. 

Since there's no valve setting for waste available, you have to improvise if you want to send the water to waste. 

DE Filters 

Diatomaceous Earth (DE) filters have grids or fingers inside the tank. Using the backwash setting on the push-pull valve will send water into the tank and then waste, but it will inundate the grids with any dirt in the water. Since there's no way to bypass the tank entirely and keep the grids clean, you can open the tank and remove the grids. 

You'll have to stop the system, purge the excess pressure, and open the tank according to the manufacturer's instructions. Then, you can remove the grids, put everything back together, and when you backwash, you'll effectively run the system to waste. 

Then you'll have to open the tank again, reinstall the grids, and resume regular operation. 

Sand Filters

Sand filters with a push-pull valve are harder to use to waste. You will have to disassemble the slide valve by opening the union and any small nuts or fittings. Then, you'll clean up any lubricant you find and use an appropriately-sized rubber expansion plug to block the valve body. 

Doing this will prevent the water from entering the tank with the sand and eliminate it through your backwash hose or pipe. Since there is a lot of pressure involved, this is a pretty dangerous technique, so make sure:

  • The waste line is not clogged or kinked
  • The plug is fully tightened with a wrench
  • Don't stand over the plug
  • Open the air bleeder valve before starting the pump

After vacuuming to waste, you'll need to put everything back together. 

Cartridge Filters

Cartridge filters don't need backwashing, so there usually isn't a valve between the pump and the tank. So, you have to get creative if you want to run the system to waste. You'll open the tank, remove the cartridge, and put the tank back together. 

Then, you'll remove the drain plug. You may need to visit the hardware or pool supply store to find an adapter that fits the threads for the drain valve on the tank. Install your new fitting, attach a hose to it, and run it to someplace where you can dump water. 

Now, turn your system on, and you're effectively pumping to waste. 

Other Types of Systems: The Right Way to Waste

The best method for pumping to waste on a system that doesn't have the correct valves is to install one. 

If you have enough room between the pump and the filter tank, you can install a three-way valve in the plumbing and a hose from the outlet. One end of the valve will receive water from the pool. In normal mode, the valve will pass water through to the pipe leading to the filter. 

When you want, you can flip the valve to the third setting, sending the water from the pool to your new outlet hose. 

Vacuum to Waste: Keep Your Filter Clean

Vacuuming to waste can spare your filter a lot of abuse. That can translate into significant savings for you by reducing the amount of maintenance you need and improving the service life of your filter. 

Even if you have to do a couple of tricks to vacuum to waste, it's usually worth the extra hassle. And adding a valve for waste isn't expensive, and it's probably something you can do DIY.

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