Does a Pool's Chlorine Harm Your Plants or Garden?

A friend recently contacted me to ask if his dreams of building a backyard escape will pose a long term health risk to his soil or plants. It would be a traditional inground pool that uses chlorine for simplicity.

Ok, this question brings in some many thoughts, I'm trying to organize my words...

First of all, sure no plant nor human wants or needs to drink chlorinated water. However if you water your plants with city water, you probably have already been giving them a little chlorine all along. Rain water is non-chlorinated which is one reason why your plants thrive after a good rain. Many indoor gardens exclusively use reverse osmosis filtered water to remove chemicals like chlorine for better plant health.

So that means no pool = bad? Well no, not unless your garden is in very close proximity to the pool AND your family plans on making cannonballs and belly flops a daily traditional. Otherwise I don't think you should worry about the plants themselves, want you really should be asking is how does chlorinated water affect soil.

For that question I decided to reach out to a pool company that was recently in the news for completing an incredible amount of pool cleanings. Blue Science, the company, also tests backyard conditions for pool construction so I'm sure that they have had to do such research before.

Blue Science pointed me to a study by Colorado State University in which they found while chlorine does kill beneficial microorganisms in your soil, the reproduction rate of these microbes is so rapid that the net effect is basically zero.

Researchers have found that chlorinated drinking water may kill a number of microorganisms in soil or a compost pile. However, their reproduction rate is so rapid that populations rebound in a short time. Under normal conditions, chlorinated water will not threaten microorganism populations. Microorganisms reproduce rapidly. In one study, researchers continuously applied highly chlorinated water to soil for 126 days. Two days after they stopped, the soil microorganism populations reached pre-treatment levels at all depths of soil.


So I would not worry about a swimming pool causing a long term debasement to your backyard's horticultural potential. If you really want to balance the affects of a little pool splash here and there, setup a whole house or hose carbon filter for your daily watering.