WHAT ARE THE STANDARDS FOR SAFE DRINKING WATER

It is known that no one method of filtering or purifying water is going to eliminate 100% of elements from our drinking water.  That said, water can be safe and acceptable, within reason.  There are guidelines, set by the U.S. EPA, which measure water standards to make sure our water is safe.

‘Acceptable’ contamination levels of water are measured by two standards: maximum contaminant level (MCL) and maximum contaminant level goal (MCLG). For the list of induvidual contaminant standards, please click here.

The goal indicates the level of contaminant at or below which is considered safe for human consumption. However, given the size of most water systems, today’s technological limitations, and the costs involved with water purification, it is impossible to provide the masses with water at or below goal level for all contaminants.

Because of these difficulties, the MCL standard was created as a compromise between public safety and feasibility, dictating levels that must be met before water is distributed to the public. This level is usually within 5% of acceptable contaminant range.

Post-Filtration Contaminants

Turbidity is a measure of the cloudiness of water, and an indication of filtration effectiveness. Cloudy water is a sign of the presence of microorganisms that can cause gastrointestinal illness. Although controlled at the original filtration source, soil runoff and other factors can affect turbidity levels by the time water reaches a faucet.

The pipelines that transport water from its original purification source to homes and businesses can affect certain contaminant levels. These include: vinyl chloride, known to increase the risk of cancer (goal level is 0; actual level is 0.02%); lead, which causes high blood pressure and kidney disease in adults and developmental delays in children (goal level is 0; actual level is 0.015 mg/L); copper, which contributes to gastrointestinal disease in the short-term and liver/kidney damage in the long-term (goal/actual level of 1.3 mg/L); and cadmium, known to cause kidney damage (goal/actual level of 0.005 mg/L).

Other factors can further contaminate water between its original purification and consumption. Fertilizer runoff and leaching from septic tanks can cause increased levels of nitrite (goal/actual level of 1 mg/L) and nitrate (goal/actual level of 10 mg/L), both of which are lethal to infants younger than six months. Water storage tank liners leak small amounts of benzoapyrene (goal level is 0; actual level is 0.0002 mg/L), which can cause reproductive complications and increased cancer risk.

The Effects of Disinfectants

Disinfectants to remove contaminants can also be harmful to humans in and of themselves. Use of disinfectants has led to the development of two additional water safety standards: maximum residual disinfectant level (MRDL) and maximum residual disinfectant level goal (MRDLG).

Just as with contaminant level standards, it is not always realistic to reach the residual disinfectant goal. In response, the MRDL offers a balance between human safety and available purification resources.

Disinfectants and their byproducts found in water include bromate, known to increase the risk of developing cancer (goal level is 0; actual level is 1%) and chlorite, which can cause nervous system damage in children as well as anemia (goal level is 0.8 mg/L; actual level is 1.0 mg/L).

Although there is a set standard for national water safety, individual standards may vary by state, county, and facility.