Don’t Use Biodegradable Soap In Lakes Or Rivers

As we’re into the season where more people will be recreating outside and heading to lakeside summer camps, today’s post is a friendly reminder to never use soap, regardless of whether its label features buzzwords such as biodegradable, natural or organic, in lakes, ponds, streams, rivers, or any other water source.

The stuff printed on the label is marketing, not science. It is designed to get you to buy the product. The use of the buzzwords above give people a warm and fuzzy feeling about the product. They don’t tell you about the product’s effect on the water. So let’s take a quick look at biodegradable and what it actually means.

The following information is quoted directly from the New Hampshire Department of Environmental Services Fact Sheet on Biodegradable Soaps and Water Quality.


What does BIODEGRADABLE Really Mean?

A material is considered biodegradable if it is “capable of being decomposed by biological agents, especially bacteria,” or if it is a “material that, left to itself, will be decomposed by natural processes.” When you really think about it, most products can be considered biodegradable; it’s just a matter of time.

When considering soaps and other cleansers, the bigger question is: How quickly does the soap break down and what conditions are necessary for breakdown to occur? And, an even more important question is: What by-products does the soap or cleanser leave behind?

Phosphorus was once a common ingredient used in many cleansers, but did you know that it is illegal to sell soaps containing phosphorus in New Hampshire? The exception to this law is for soaps used in automatic dishwasher detergent. As a rule of thumb though, it is always a good idea to check the label and make sure phosphorus is not a listed ingredient.

Phosphorus has been banned because it is a “limiting nutrient” associated with aquatic plant and algal growth. Phosphorus-loading in freshwater systems like lakes, ponds, and rivers leads to increased plant and algal growth, oxygen depletion and ultimately accelerated lake aging. If you are caught using soap containing phosphorus in New Hampshire, other than automatic dishwasher detergent, you may be fined. Aside from the legal issues, it is also important to consider that, with the exception of a few backpackers’ soaps, most of these products are meant to be used in the home, not outdoors.

Dilution is NOT the Solution to Pollution!

While it was once thought that dilution would take care of most pollutants in surface waters, over time this theory has been found to be untrue. If you are the only person washing in a cool mountain stream with a bar of organic soap or the only person on your pond washing a boat with a bio-degradable cleanser, that one isolated incident may not have a detectable impact on the quality of the water. However, if everyone recreating nearby washed themselves in the river or cleaned their boat in the pond with biodegradable soap, the water could reduce or lose the ability to breakdown the soaps and cleansers. It should be noted, too, that it is illegal in New Hampshire to add any-thing to freshwater, including soaps and cleansers.


A good, simple rule about putting things in the water is if you wouldn’t drink it, don’t get it anywhere near the water. If you use soap for dishes or bathing, make sure you’re a good distance (at least 200 feet) from the water.
For more information on how soap works, check out this link from Elmhurst College.

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