Each year the Missouri Department of Natural Resources publishes the Census of Missouri Public Water Systems. I reported on the 2013 census here, and the 2014 census here, and the 2015 census here. This post reports on the 2016-2018 censuses. The census provides basic information about the number and type of public water systems in the state, plus information on each system that includes the source of its water, the type of treatment it gives the water, and a chemical analysis of the water that covers 16 inorganic chemicals.

The EPA defines a public water system as one that provides water for human consumption to at least 15 service connections or that serves an average of at least 25 people for at least 60 days a year. It classifies public water systems in three categories. Community Water Systems (CWS) supply water to the same population year-round. Non-Transient Non-Community Water Systems (NTNCWS) supplies water to at least 25 of the same people at least 6 months per year, but not year-round. An example might be a school that has its own water system. A Transient Non-Community Water System (TNCWS) provides water in a place where people do not remain for long periods of time. Examples might include gas stations or campgrounds that have their own water systems. Not included in the report are private systems, such as a privately owned well that provides water only to its owner.

Table 1 shows the number of public water systems in Missouri by category. In 2018 there were 2,732 public water systems in Missouri, about 52% of which were community water systems. The numbers have not changed greatly over the years.

Table 1.

Table 1. Data source: Missouri Department of Natural Resources, 2013 through 2018.

A primary water system is one that obtains water from a well, infiltration gallery, lake, reservoir, river, spring, or stream. A secondary water system is one that obtains its water from an approved water system, and distributes it to consumers. (Missouri 10 CSR 60-2015, Definitions) For instance, in 2018 the St. Louis City Public Water System was a primary system. It obtained 100% of its water from surface water supplies, and treated the water itself. On the other hand, the Kirkwood Public Water System was a secondary system. It purchased 100% of its water from Missouri American Water, which treated the water before selling it to Kirkwood. Kirkwood only distributes the water.

In 2018, about 78% of Missouri public water systems were primary systems, and they served about 79% of the population. Table 2 shows the number of systems by water source, and Table 3 shows the population served by each type.

Table 2.

Table 2. Data source: Missouri Department of Natural Resources, 2013 through 2018.

Table 3.

Table 3. Data source: Missouri Department of Natural Resources, 2013 through 2018.

Groundwater means groundwater that is not directly influenced by the surface water above it. The groundwater is isolated from surface groundwater by thick layers of rock or sediment that filter the ground water before it reaches the groundwater aquifer. Such groundwater is often considered less vulnerable to pollution by chemicals and organic waste. Groundwater Under Direct Influence refers to groundwater that is not protected from the surface water above it, and which consequently contains groundwater contaminants, such as chemicals, insects, microorganisms, algae, or turbidity. This kind of water requires more extensive treatment before it is fit for use. So does surface water. Groundwater is a limited resource, however, that sometimes takes hundreds, if not thousands, of years to percolate into underground aquifers. Overuse can deplete it. (See here.)

In 2018, groundwater systems constituted 84.5% of the total number of systems, but they served only 37.1% of the population. On the other hand, surface systems constituted 15.2% of the systems, but served 62.4% of the population. Table 3 shows the population served by water source.

Most of the water systems in Missouri source their water from groundwater, only a few from ground water under direct influence. However, the source serving the largest population is surface water. Specifically, the Missouri River is the water source for much of the Kansas City and St. Louis metropolitan areas. More than half of Missouri’s population is served by water either from the Missouri River Alluvial Aquifer or water from the river itself.

Source:

Missouri Department of Natural Resources. 2013. 2013 Census of Missouri Public Water Systems. Downloaded 2018-06-13 from https://dnr.mo.gov/env/wpp/census.htm.

Missouri Department of Natural Resources. 2014. 2014 Census of Missouri Public Water Systems. Downloaded 2018-06-13 from https://dnr.mo.gov/env/wpp/census.htm.

Missouri Department of Natural Resources. 2015. Census of Missouri Public Water Systems, 2015. Downloaded 2018-06-13 from https://dnr.mo.gov/env/wpp/census.htm.

Missouri Department of Natural Resources. 2016. 2016 Census of Missouri Public Water Systems. Downloaded 2018-06-13 from https://dnr.mo.gov/env/wpp/census.htm.

Missouri Department of Natural Resources. 2017. 2017 Census of Missouri Public Water Systems. Downloaded 2018-06-13 from https://dnr.mo.gov/env/wpp/census.htm.

Missouri Department of Natural Resources. 2018. 2018 Census of Missouri Public Water Systems. Downloaded 2018-06-13 from https://dnr.mo.gov/env/wpp/census.htm.