Because water quality strongly impacts the health of you and your family, it is important to know the quality of the water used for domestic consumption. In the United States and elsewhere, drinking water can come from:
- a public supply system
- private sources
- from the household well
In the United States, if water comes from a public system, then the water is tested by the supply authority. The results are then documented in federal and/or state records. Consumers must be alerted to the presence of any contaminants in the water being supplied.
If the supply comes from a private source, the water may not be tested, so water quality is questionable. This puts the responsibility on the consumer to test the water on a periodic basis for some common contaminants.
What to Test and When to Test it
Testing should be performed once or twice a year. If the water supply is adjacent to a septic tank, then the water should be checked for coliform bacteria. If there is an infant in the house, then the water should be tested for nitrates. The presence of nitrates beyond permissible levels can cause blue baby syndrome in infants. If the plumbing infrastructure is made of lead, it’s important to test for lead contamination in the water.
Even without testing, there may be telltale signs of the presence of some contaminants. It is important to associate the symptom to the correct cause.
Some common contaminants and their associated symptoms are:
Symptom | Contaminant |
Grayish white film in sinks/ tubs, scales in teapots | Hardness due to calcium and magnesium |
Brown or reddish stains | Iron |
Black stains | Manganese |
Salty taste, corrosion of metals | Chloride |
Gurgling noise in well | Dissolved gases in water (like methane, carbon dioxide) |
Rotten egg odor | Hydrogen sulphide gas |
Gastro intestinal illness | Coliform bacteria |
Water quality can be tested by sending samples to water testing laboratories. Alternatively, hand held test kits work for testing most, if not all, of the critical parameters.
Some of the parameters that can be tested are:
- dissolved oxygen
- total dissolved solids
- turbidity
- electrical conductivity
- pH
There are compact instruments capable of measuring close to 17 parameters. Some of these instruments also have a feature to remotely log and transfer data.
Illustration: Hand held TDS and pH meter
Once measuring contaminant levels in the water becomes a habit, it’s important to keep a log to identify any pattern deviations. This will also increase awareness about different sources.
For instance, one of our colleagues measured the Total Dissolved Solids (TDS) in his tap water and in bottled water. The values for tap water ranged from 120-550 parts per million (ppm). The values for the bottled water ranged from 5-15 ppm. (Parts per million is a notation to describe very small quantity measures. Ppm corresponds to 1 milligram per liter.)
These results do not necessarily indicate that tap water is bad, they’re just an indication of its inherent quality. In fact, some of the minerals in the water that contribute to its relatively higher TDS (when compared to the almost sterile store bought water) are good for the human body. One simply needs to rule out the presence of any harmful contaminant beyond a certain level.
After obtaining the measurements, the next logical step is to compare it with the drinking water quality standards mandated by Environmental Protection Agency (EPA). The EPA has listed all possible contaminants and their respective MCLG (Maximum Contaminant Level Goals) and their MCL (Maximum Contaminant Levels). MCLG is the level of contaminant below which there is no known health risk. MCL is the highest level of contaminant that can be present in the water supply and this standard is enforced. In simple terms, MCLG and MCL can be thought of as desirable standards and permissible standards respectively.
Total Dissolved Solids (TDS)
Let’s discuss one of the most common parameters that can be present in water and its implications – Total Dissolved Solids (TDS).
On a broad level, dissolved solids refer to anything that is dissolved in water (apart from any suspended solids and water itself). Thus, any minerals, salts, metals, ions, etc. dissolved in water constitute or contribute to its TDS value. A wide range of sources contribute to TDS in water. They can be organic sources like:
- biological waste
- plant waste
- industrial effluents
- fertilizers and pesticides
Inorganic sources can be rocks (in the case of ground water) and from impurities in air. TDS can also be the result of leaching from the plumbing fixtures through which water flows and reaches the household. An infamous episode of water contamination due to plumbing fixtures was caused by lead fixtures that were the norm until a few decades ago.
Why measure TDS
TDS is an umbrella term for the different contaminants that can cause a high TDS result. In the absence of instruments which measure individual parameters, keeping tabs on TDS alone with a hand-held testing kit is generally adequate.
The EPA mandates a MCL for TDS of no more than 500 ppm. Anything above 1000 ppm is strongly unfit for human consumption. Once the presence of high TDS is established in your water source, further samples can be sent to a water testing laboratory. The root cause of the high TDS can be identified and specific mitigation/ elimination measures can be undertaken.
References:
- https://www.epa.gov/sites/production/files/2015-11/documents/2005_09_14_faq_fs_homewatertesting.pdf
- http://www.tdsmeter.com/what-is