“Is it illegal to empty street pools and sewers?” If so, I think the public should be aware, âsays reader
Editor’s Note: The following is science columnist Peter Bursztyn’s response to a question in his reader’s mail bag. If you have a question for Peter, email us at [email protected]
As I walk through Barrie’s old east end, I see swimming pools draining into the sewers.
Doesn’t that also add to the chlorine in Lake Simcoe?
Is it illegal to drain street pools and sewers? If so, I think the public should be aware. – DorothÃ©e M.
Hi Dorothy. This is an interesting question and requires a multi-part answer.
First, a little chemistry lesson. âChlorideâ is measured instead of common salt (sodium chloride). It’s easier. Sodium chloride is made up of one atom of sodium and one atom of chlorine. Both atoms are highly reactive. When they meet, they react to form sodium chloride.
It is a âpolarâ substance, just like water (hydrogen + oxygen = H2O). Polar substances have a positively charged end while
the other is negative. When a salt crystal is put in water, the water tears apart the sodium and chloride ions. They then “float” in the solution.
These ions are not reactive and are considered harmless. However, if you hold metallic sodium in your hand, it
cause a severe burn. Chlorine gas is also very reactive. The armies of World War I released chlorine gas to blow towards the enemy. When inhaled, chlorine seriously damages the lungs, often killing victims.
Chloride ion is not the same as chlorine gas. Chlorine gas is used to disinfect water by killing any microbes present. Most drinking water plants around the world add a little chlorine just before they send their water to you. Chlorine remains trapped as long as the
the water is contained in the plumbing. Chlorination of water protects us from water-borne illnesses.
Second, what happens to the chlorine added to the water?
The added chlorine atoms are very reactive. As soon as they come across “stuff”, they react with it. When you add bleach to water, it reacts with the dyes in clothes, bleaching them. Of course, we use overwhelmingly more chlorine to bleach clothes than the city adds to consumption. Chlorine in drinking water reacts with your saliva, destroying itself without harming you.
Swimming pools generally contain 10 times more chlorine than drinking water. This is why you can smell the astringent chlorine
smell in an indoor pool. This amount of chlorine can be harmful to the eyes of people who swim in swimming pools for long periods of time. Competitive swimmers wear small goggles to protect their eyes from chlorine.
You don’t have to, because most people don’t spend hours training in the water and usually close their eyes when they’re underwater.
Competitive swimmers keep their eyes open to stay in their lane and avoid bumping into the bottom of the pool.
Chlorine is constantly escaping from a swimming pool, which is why operators must add chlorine. Tap water also loses its chlorine through evaporation. Any remaining chlorine is gone as soon as it encounters organic “stuff” in the wastewater stream. There is none left when the water reaches the treatment plant.
And third, you are right. The Ministry of the Environment prohibits the discharge of swimming pool water into the sewers.
However, almost everyone does. Three of my neighbors have pools in the back and all of them drain their pools into the street sewer. Despite this, I doubt that chlorine actually reaches the treatment plant. It evaporates or reacts with organic matter in storm sewers before reaching the treatment plant.
I asked our wastewater treatment plant manager if the chlorine added to evacuate the water survived in the lake. He told me that the city of Barrie does not chlorinate its wastewater. Our wastewater treatment plant sterilizes the waste water by ultraviolet radiation, so no residue.
In addition, some swimming pools no longer use chlorine. Saltwater pools add salt to the water. This tends to kill any germs that might fall into the pool. These pools are much less salty than the sea. However, when they discharge water into the sewers, and eventually into Kempenfelt Bay, they add salinity, which I first mentioned.