Phosphates in Folsom pool water
June 14, 2022
Why are there phosphates in Folsom water?
In 2020, many Folsom residents experienced pin-hole leaks in their copper plumbing pipes. How did this happen? (no, it wasn’t Covid related!) Allegedly, the water is soooo pure coming out of the American River and Folsom Lake that it created a water chemistry issue which led to pitting in the pipes (what I want to know is why did this just start happening? The water coming down the American River is pretty much the same as it’s been the last 50 years, right? So why now?)
Anyways- the City of Folsom solved the issue by adding Orthophosphate to our drinking water. For the most part it has solved the copper pitting issue but its created another consequence: the introduction of phosphates to our swimming pool water.
What are phosphates?
Phosphates are food for algae and other micro organisms. When they get into your swimming pool water, even in trace amounts, they can wreak havoc on the quality of your pool water and water chemistry. The more phosphates that are in your pool water, the more chlorine is needed to keep the water clear and sanitized.
How do they get into your pool?
Before orthophosphates were added to our Folsom drinking water, phosphates in pool water were the byproducts of things like soaps, shampoo’s, and fertilizers. We (swimming pool service companies) treated them as they occasionally materialized. With the introduction of orthophosphate to drinking water, treating phosphates in pools has become a monthly and even weekly occurrence.
What are some issues you’ll see?
If you are struggling to maintain clear water and /or keep a chlorine residual in your pool you may have phosphates. 
Phosphates are algae food. The more phosphates in the pool, the more algae grows. The more that algae grows, the higher chlorine demand to kill the algae and sanitize your swimming pool water. A low phosphate level typically equals less chlorine needed to treat the pool. So, keeping phosphates out of the pool will save you money in chlorine!
What is the recommended range?
Is there an allowable amount of phosphates in your pool water? Yes, and it’s 100ppb. Notice the “b” there. That means “parts per billion.” That’s a tiny amount. Think about it! That’s 1 drop of phosphates in 1 billion drops of water. In my experience, phosphates are manageable up to 500ppb. When the level is above 500ppb you’ll need more chlorine to keep the water clear and algae-free.
How do you treat them?
Fortunately there are effective chemicals available to remove phosphates from your pool water. If you live in Folsom, unfortunately the next time you add water to your pool you’re also adding phosphates back into the pool☹️.
The Solution
Sadly, if you live in Folsom or a municipality that treats your drinking water with orthophosphate, I don’t foresee a solution. I’ve spoken to a Folsom city council member who said the City has no plans to discontinue the application of orthophosphate in our drinking water. So, keep buying phosphate removers to keep the phosphates low which will decrease chlorine demand and expense.
(portions of this article were reprinted with permission from the King in Seminole, Florida)
