# Determining if water is safe to swim in **URL:** \ **Category:** Factual Questions\ **Created:** [September 17, 2008, 8:55pm UTC](https://boards.straightdope.com/t/determining-if-water-is-safe-to-swim-in/464034 "2008-09-17T20:55:36Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Influential\_Panda](https://avatars.discourse-cdn.com/v4/letter/i/8e8cbc/32.png) [@Influential\_Panda](https://boards.straightdope.com/u/Influential_Panda)\ **Post date:** [September 17, 2008, 8:55pm UTC](https://boards.straightdope.com/t/determining-if-water-is-safe-to-swim-in/464034/1 "2008-09-17T20:55:36Z")
Howdy. I’m doing a presentation for kids at a local private school on how to determine if water is safe to swim in. There was recently a leak a local creek that spilled millions of gallons of raw sewage into what (was) the cleanest water in Alabama. The creekkeeper told me that you can spot sewage by the film on top and the green stuff starting to grow on the floor. I was wondering if there are any other ways of deciding if water is safe to swim in, short of calling and having a pollution test done. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [September 17, 2008, 9:06pm UTC](https://boards.straightdope.com/t/determining-if-water-is-safe-to-swim-in/464034/2 "2008-09-17T21:06:44Z")
> [@Influential\_Panda](#): > > Howdy. I’m doing a presentation for kids at a local private school on how to determine if water is safe to swim in. There was recently a leak a local creek that spilled millions of gallons of raw sewage into what (was) the cleanest water in Alabama. The creekkeeper told me that you can spot sewage by the film on top and the green stuff starting to grow on the floor. > > I was wondering if there are any other ways of deciding if water is safe to swim in, short of calling and having a pollution test done. Wouldn’t the film on top really only indicate if there was something oily in the water? If something clear and water soluble leaked into the creek, I really doubt you’d be able to tell just by looking. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [September 18, 2008, 2:12am UTC](https://boards.straightdope.com/t/determining-if-water-is-safe-to-swim-in/464034/3 "2008-09-18T02:12:14Z")
> [@Influential\_Panda](#): > > Howdy. I’m doing a presentation for kids at a local private school on how to determine if water is safe to swim in. There was recently a leak a local creek that spilled millions of gallons of raw sewage into what (was) the cleanest water in Alabama. The creekkeeper told me that you can spot sewage by the film on top and the green stuff starting to grow on the floor. > > I was wondering if there are any other ways of deciding if water is safe to swim in, short of calling and having a pollution test done. No–you have to test the water. This would consist of testing for fecal coliform and/or _E. coli_, which are an indication of fecal matter in water and of possible pathogenic organisms. ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [September 18, 2008, 3:46am UTC](https://boards.straightdope.com/t/determining-if-water-is-safe-to-swim-in/464034/4 "2008-09-18T03:46:41Z")
If I’m remembering correctly, the most common reason for beach closures is actually bacterial count - which cannot be determined just by looking at the surface of the water. You actually need to test the water for bacteria. Sure, an oily sheen doesn’t look good and you probably don’t want to swim in it, and a dramatic red tide is visible to the naked eye, but in the absence of both those things the water can still be too dangerous to swim in. ☹ ---
**Author:** ![Darryl\_Lict](https://avatars.discourse-cdn.com/v4/letter/d/7cd45c/32.png) [@Darryl\_Lict](https://boards.straightdope.com/u/Darryl_Lict)\ **Post date:** [September 18, 2008, 4:50am UTC](https://boards.straightdope.com/t/determining-if-water-is-safe-to-swim-in/464034/5 "2008-09-18T04:50:26Z")
Our beaches get closed quite often after a severe winter storm. The water looks murky, but you couldn’t tell it had a dangerously high bacterial/viral count. Lots of surfers get Hepatitis A because it’s rather compelling to surf during a winter storm. There’s another disturbing infection that is starting to crop up. [Brain destroying amoebas](http://www.efluxmedia.com/news_Elsinore_Boys_Death_from_Amoeba_Prompts_Officials_Warnings_21626.html) have been killing people in warmer freshwater. Thank god they don’t survive in saltwater.