While the concept of municipal water dates back thousands of years, there was not a single, central law on the books in the United States until 1974.  This law is known as the Safe Water Drinking Act (SWDA) and is administered by the EPA.

Of note, this solely covers drinking water.  There is not one law on the books creates a municipal responsibility to mitigate the damage done by hard water.  Scale or destruction to hot water heaters, dishwashers, or washing machines are all outside of the scope of the SWDA.

The SWDA applies to over 160,000 distinct public water supplies.  Even a subdivision with a shared well servicing 26 or more homes will become a public water supply and thus be subject to testing.

The original 1974 law was designed to ensure the delivery of reasonably safe water to the tap for those on municipal supplies. There are some limits to the Safe Water Drinking Act.  As was always the case, and more formally reinforced in 1996, there is an economic feasibility test to determine if the benefits of any requirement outweigh the related costs.

The threats from water are varied.  These can range from improperly disposed chemicals, human or animal waste, herbicides, pesticides, insecticides and even naturally-occurring substances.  An example of the latter is the radium regulation that we’re seeing in Waukesha water.

The SWDA hasn’t been without change.  In 1986, additional regulations were added that covered filtration and disinfection processes.  Another change from 1986 was a restriction on the amount of lead in solder.  Effective this year, new laws applied to all fixtures and fittings that further reduced the risks from lead.

Another important, regulated aspect of the SWDA is the distribution of water.  All the disinfection in the world at the distribution facility would be useless if the entire distribution system was exposed.  While cities do test for bacteria at the plant-level, they also have to have important safeguards in place for situations where a main is compromised or where pressure has been lost.

This concept also applies to testing.  The entirety of regulations spans across a few things and fall into six parts.

Microorganisms The SWDA does have regulations at a production level for bugs in the water like cryptosporidium, giardia, legionella, coliform bacteria and enteric viruses.

Disinfectants  For transportation of water, chlorine, chloramine, and chlorine dioxide are all regulated.

Disinfection by-products  Virtually any disinfection process creates disinfection by-products.  Many of these are as scary as what we were originally treating.  So many folks will know that trihalomethanes are a disinfection by-product from chlorine treatment.  Additionally, bromate is a regulated substance formed from the use of ozone–so we see this one in Milwaukee.

Inorganic Chemicals  This group will include some of the more recognizable words in water treatment.  In this category, we’re dealing with things like arsenic, copper, cadmium, cyanide, lead and mercury.  Additionally, we’re dealing with things like nitrates and nitrites.

Organic Chemicals  There are 53 organic compounds that make the EPA’s list.  These will include benzene, multiple dioxins, PCBs and a handful of pesticides.

Radionuclides This is the ‘ums’ section of the periodic table.  Radium and uranium, both naturally occurring in the ground are regulated under this section of the SWDA.

Perhaps the most important thing to remember in any discussion of municipal water is to understand what is reasonable.  There are literally tens of thousands of chemicals that are known to present health risks to humans.  It is not reasonable to test for every chemical or compound.


There are countless organisms that live in water.  It’s not even possible for them to test for every bacteria or virus in the water.  Instead, your city will test for coliform, an indicator of fecal/sewage contamination and use methods like UV light in doses that are strong enough to kill e coli, coliform, and giardia.

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