Empty your pool, spa or hot tub the right way

A backyard pool
A backyard pool.

I know it’s still the middle of summer and some of you might be enjoying your ‘staycation’ in your backyard swimming pool. However, at some point, you are going to have to empty some or all of the water from your swimming pool, hot tub or spa (referred to as pool water from now on). Do you know there are environmental issues to consider?

Before providing some tips, please let me backtrack a little. I feel that I need to first explain the difference between a storm sewer and a sanitary sewer. Many use these terms interchangeably but there is a very important difference between the two.

A sanitary sewer is where all the water used inside your home or business ends up after it has been used (examples: toilets, sinks, showers, dishwasher and washing machine). This water flows to a wastewater treatment plant, where it is cleaned and tested before being released back into Lake Ontario.

Sanitary sewer
A sanitary sewer (water flowing through this system is treated at a wastewater treatment plant).

A storm sewer collects rainwater and snowmelt usually through catch basins on our streets, and drains directly into a local creek or water body without being treated. In our region, this untreated water eventually flows into Lake Ontario.

A storm sewer (material flowing through this system is not treated).
A storm sewer (water flowing through this system is not treated at a wastewater treatment plant).

There is an environmental awareness program designed to teach residents about this important fact called the Yellow Fish Road program. Stay tuned for a future blog post about this program and how you can get involved.

Stencil used for the Yellow Fish Road program
Displaying a “rainwater only” stencil that is part of the Yellow Fish Road program.

Okay, now that I’ve digressed a little bit – with what I hope was some helpful information – it’s time to get back to the original topic of emptying your pool, spa or hot tub the right way.

A hot tub
A hot tub.

Chlorine or Bromine Pools

Pool water contains several products, such as chlorine, which help to keep the pool clean. However, if released directly into the storm sewer (the one that’s not treated and ends up directly in water bodies), pool water can have a severe impact on the microorganisms, plants and fish in our ecosystem. If you have a chlorinated pool, dechlorinate the water by letting the pool water sit for a week or two, preferably under sunny conditions. This will allow the chemicals to evaporate lowering their concentration in the water. Test your pool water to ensure that levels are close to zero. At this point, you can slowly release the water on your lawn to be absorbed into the ground or to a storm sewer on a day when rain is not forecast. When you release pool water onto your property, there is an added benefit because you are also watering  your grass. Pool water discharge is not permitted on private property, without the consent of the owner, or on sensitive lands such as a ravine, valley, wetland, watercourse, etc.

A backyard pool.

Backwash water

Backwash water, which is created when rinsing the filter with clean water, contains sediment and chemicals. This water must be filtered and dechlorinated, as mentioned above, if it is going to be released in the storm sewer. Otherwise, it must be discharged into the sanitary sewer, as mentioned below, or across the lawn on your property.

Saltwater pools

Unlike chlorine pools, letting a saltwater pool’s water sit will not alter the salt levels within the water. As a result, saltwater pools must be slowly emptied into the sanitary sewer connected to your home or removed by an approved waste hauler. Under no circumstance can a saltwater pool be discharged into a storm sewer or directly into a ravine or creek. The saltwater itself can kill aquatic organisms. Saltwater pools should only be drained during dry weather and never during a storm. For homes with a sanitary lateral (commonly called a sewer pipe) cap, the homeowner can remove the cap with a wrench and slowly drain the saltwater pool through this pipe. Another option is to drain the pool through a laundry tub in the basement. Never drain directly through a sanitary manhole which is pictured above.

Backyard pool
A saltwater backyard pool.

For more information

The City of London (Ontario) has produced a great video called Drain Your Pool the Right Way that explains everything I highlighted above. So, if you have just under three minutes to spare, and have a pool, spa or hot tub, I highly recommend you view it.

Enjoy the rest of summer.

Take Action Burlington. Collectively, we can make a difference.


Backyard pool
A backyard pool.

One thought on “Empty your pool, spa or hot tub the right way

  1. Hi, what about the effect on trees and shrubs when a neighbor drains their pool and the water leeches onto our property? We have lost a couple of trees when our neighbors have flooded the lower part of our back yard with pool water, and also we are still losing cedars in this area.


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