Eutrophic Drinking Water

Providing safe drinking water is a major industry in the USA, and that industry rises to many challenges. The vast majority of drinking water flowing out of faucets is extremely safe and reliable, despite the occasional catastrophes (Toledo OH and Flint MI receiving the most publicity in recent years). The Safe Drinking Water Act (SDWA) was promulgated and amended several times to legislate what consumers get, and has a lot of beneficial provisions. However, there can be unintended consequences.

For example, the SDWA calls for corrosion prevention measures to minimize leaching of lead and copper from distribution pipes. It would be better to replace those pipes, but it is true that some drinking water is acidic and some leaching could occur from any metal pipe, so adding substances that coat the pipes or minimize leaching makes sense. However, the cost of anti-corrosion additives is not negligible, and it turns out that the most common (read “least expensive”) anti-corrosion agent includes a lot of phosphate. The concentration of phosphorus in water sent to customers for potable consumption can be more than 300 ug/L. That level of phosphorus is not unhealthy for people, but algae blooms can be caused by as little as 20 ug/L.  Algae are not going to bloom in dark distribution pipes, but once that water sees the light of day, growth is possible. Watered lawns may need less fertilizer as a result, but any runoff from such watering could wreak havoc on the receiving stream or lake. Flushing fire hydrants, an occasional operational need, can put a lot of phosphorus in the nearest water body.

We know that drinking water from a lake without treatment may be hazardous to our health, but how many of us know that the water we receive from most public supplies may be hazardous to the lake.


Is your tap water safe for your lake?

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