Water Quality Testing

Drinking water can come from different sources depending on where we live in the world. Three sources that are used to collect drinking water are:

• Groundwater
• Surface water
• Rainwater

Water is in continuous movement on, above, and below the surface of the earth. As water is recycled through the earth, it picks up many things along its path. Water quality will vary from place to place, with the seasons, and with the various kinds of rock and soil it moves through.

For the most part, it is largely natural processes that affect water quality. For instance, water moving through underground rocks and soils may pick up natural contaminants, even with no human activity or pollution in the area. In addition to nature's influence, water is also polluted by human activities, such as open defecation, dumping garbage, poor agricultural practices, and chemical spills at industrial sites (see also water source protection).

Even though water may be clear, it does not necessarily mean that it is safe for us to drink. It is important for us to judge the safety of water by taking the following three qualities into consideration (see also pathogens and contaminants):

• Microbiological – bacteria, viruses, protozoa, and worms
• Chemical – minerals, metals and chemicals
• Physical – temperature, colour, smell, taste and turbidity

Safe drinking water should have the following microbiological, chemical and physical qualities:

• Free of pathogens
• Low in concentrations of toxic chemicals
• Clear
• Tasteless and colourless (for aesthetic purposes)

When considering drinking water quality, microbiological contamination is the main concern in most cases since it is responsible for the majority of illnesses and deaths related to drinking unsafe water. Learn more about water purification.

Qualitative observations

The first step to check water quality can be done by very simple observations:

Qualitative observations. Source: CAWST (2009)

Portable testing kits

Analyses for many physical, chemical and microbiological contaminants can be carried out in the field or in a temporary laboratory using specifically designed products that are portable and relatively easy to use. A significant advantage of field analysis is that tests are carried out on fresh samples whose characteristics have not been contaminated or otherwise changed as a result of being stored and transported over long distances (CAWST 2009). Read more about the specific test kits in CAWST (2009).

Portable water quality test kits should have the following characteristics (CAWST 2009):

• Easy to use with simple instructions
• Small and easy to transport
• No restrictions on air transport
• Fast results
• Limited requirement for distilled or deionised water
• Dilution not necessary
• Does not require calibration
• Robust (limited effects from UV light,shock,humidity or temperature)
• Can test several parameters
• Easy to repair or replace
• Limited consumables or consumables are easy to obtain

Mobile laboratories

Water and environmental surveys frequently require the analysis to be carried out in remote areas. The use of a well-equipped mobile laboratory is often the ideal solution. More and more, they are becoming widely used, especially in developing countries where accurate results are required quickly, usually in areas where no fixed laboratory facilities exist (WAGTECH n.y.).

Laboratory Testing

Water quality testing can also be carried out in a laboratory. This method requires facilities, trained technicians, equipment and other supporting materials. Laboratory testing can be useful if you are only taking a small number of samples and your project is located close to an urban area where a laboratory is present (CAWST 2009).

Summary of advantages and limitations of laboratory testing. Source: CAWST (2009)

Portable kits

Depending on the manufacturer and funding, portable tool kits can be very pricey for local organisations or NGO’s.

Mobile laboratories

Government agencies and research centres responsible for monitoring and water quality testing sometimes use mobile laboratories for periodic water quality testing. The vehicle is usually the most costly piece of equipment (CAWST 2009).

Laboratories

The initial costs to equip a laboratory are very high. The cost of a laboratory sample tests varies depending on the following parameters:

• Geographical location of the laboratory
• Types of chemical or biological contaminants
• Quantity of sample tests
• Accuracy and precision level required

The costs are usually reduced as the numbers of tests increase.

Trained people can perform qualitative observations and tests with the help of portable tool kits. Laboratory work (mobile or immobile) must be carried out by experts. The equipment must be cleaned and maintained after being used. Instructions of the manufacturers must be considered.