Because of modern chemistry, it is now possible to detect all sorts of chemicals and other pollutants in water, even just traces of them. The growing number of available tests can be quite overwhelming, and many of them need to be done in well-equipped laboratories. Fortunately, testing for all sorts of pollutants isn’t necessary—a smaller, more practical number of tests should be more than enough to provide us a good perspective on the chemicals that could be present in water. Even better news is the availability of low-tech versions of these tests, which even those with limited budgets can afford.
Common portable, low-tech field testing methods for water quality testing fall into these three categories.
* Test strips. A water test strip is a small, single-use piece of paper or plastic that changes colour in order to indicate how much of a specific chemical is present in water. Depending on the type of test, a user “activates” the strip of plastic or paper by either dipping it in a sample of water then swishing it around or holding the strip deep in flowing water. Once a short time has passed (you can find this information in the manufacturer’s instructions), the colour of the test strip changes, and at this point, a user should then interpret the colour change by placing the strip next to a colour chart, which shows chemical concentration.
While a very simple testing method, it isn’t that accurate compared to others.
* Colour disk kits. A colour disk test kit is available for a number of chemical testing methods. In the usual set-up, a user adds a packet of powder or a number of drops of reagent to a sample of water in a plastic tube. The sample tube is then placed in a plastic viewing box, which contains a plastic disk printed with a colour gradient. A user rotates this disk until he finds the part which matches the sample colour best, then reads the interpretation printed.
The use of a colour disk kit usually involves several steps and prescribed waiting times, so they’re quite costly and complicated. They are, however, more accurate.
* Handheld digital instruments, specifically photometers and colorimeters. The results they produce are the most accurate out of all options, but cost much and are more delicate than the options mentioned above—they require batteries and calibration.
Chemical Water Quality Parameters
Having known the different test formats, the next thing to know is the things that you need to test for. According to UNICEF, it’s advised that you test for arsenic, flouride, and nitrate. Chronic exposure to these substances can be dangerous to one’s health.
Here are the ways to test for the substances mentioned above.
* Flouride. More than one colour disk testing kit is available for use in testing flouride. But a portable digital colorimeter is often the best choice due to accuracy concerns.
* Arsenic. There are a limited number of options for field testing arsenic; the laboratory is the best place to measure the contaminant. While there are commercially-available options, they are quite complex and involve several steps. Worse, the concentrations measured using these kits might be inaccurate. Fortunately, the kits detect arsenic content in almost all samples that measure more than a hundred micrograms per litre, plus most samples from 50-99 micrograms per litre, which is the drinking standard in most countries affected by the natural contamination of arsenic.
* Nitrate. Testing nitrate can be done using colour disk testing kits, test strips, and digital meters. High nitrate levels are usually associated with pollution from fertilizers and animal wastes. Sewage, landfills, industrial pollution, and even latrines contribute to nitrate presence.
If you have enough resources, UNICEF suggests the addition of three chemical parameters. The presence of these three substances in water causes odour and taste problems.
* Manganese and Iron. Colour disk tests, testing strips, and digital instruments can be used to test for these metals.
* TDS. This substance is a mix of inorganic salts, but mostly chloride, sodium, calcium, magnesium, and potassium. Instead of testing the specific components, TDS monitoring is done by measuring water conductivity using a digital meter.
Here are a couple more chemical parameters that can be monitored. These apply only to chlorinated distribution systems.
* pH. Testing water pH is easy due to the fact that colour disk testing kits and testing strips are commonplace. However, if you’re looking into a more high-tech option, you can use an electrode-based pH meter.
Remember that pH testing for water aims at assessing how basic or acidic stored water is. This is important because pH affects how other chemical constituents behave, plus the effectiveness of residual chlorine in combating harmful micro-organisms.
* Chlorine. There are numerous options for testing chlorine, including colour disks, testing strips, as well as kits designed to test swimming pools. For a more reliable measurement, you can use a digital meter that measures chlorine.