Testing Water Quality: Diy Methods To Assess Pollution Levels

Water quality testing is essential to ensure that the water we drink and use is safe and meets certain standards. There are various methods for testing water quality, including physical tests, chemical tests, and bacteriological tests. Physical tests indicate properties detectable by our senses, such as colour, turbidity, odour, and taste. Chemical tests determine the amounts of minerals and organic substances in the water, while bacteriological tests reveal the presence of bacteria, which could indicate faecal pollution. Water quality testing can be done by using at-home testing kits or sending samples to laboratories for more accurate and extensive testing. Regular testing is crucial to identify potential problems and ensure the safety of our water sources.

Testing the water temperature

Water temperature is critical because it dictates the types and diversity of aquatic life. Organisms, from microbes to fish, have specific temperature ranges for optimal health. For instance, some fish species thrive in colder water, while others prefer warmer temperatures. If temperatures deviate from the optimal range for extended periods, organisms experience stress and may even die.

How to Test Water Temperature

Water temperature can be measured using a thermometer or a meter. Alcohol-filled thermometers are safer than mercury-filled ones, as they pose less risk if broken. When testing, it is important to measure at the same depth and location each time. Here are the steps to follow:

• Prepare your equipment: Ensure you have a thermometer or meter, and a data sheet to record results.
• Sample location: Take your measurements away from the streambank, in the main current. An ideal spot is the outside curve of the stream, where the main current often flows. If the stream is shallow, wade carefully into the center to measure.
• Measurement depth: Place the thermometer or meter probe at least 4 inches below the water surface, or halfway to the bottom in a shallow stream.
• Allow time to stabilise: If using a thermometer, leave it in the water for at least one minute to reach a stable temperature. With a meter, wait for the reading to stabilise.
• Read the temperature: Try to read the temperature while the thermometer bulb is still underwater. If this isn't possible, remove the thermometer quickly and read the temperature.
• Record the data: Note the temperature on your field data sheet, along with other relevant details like time, weather conditions, and any environmental observations.

The Impact of Water Temperature

Water temperature has a significant impact on the water body and its ecosystem:

• It affects the maximum dissolved oxygen concentration, with higher temperatures reducing oxygen levels.
• It influences the rate of photosynthesis by aquatic plants, with warmer waters having less dissolved oxygen.
• It impacts the metabolic rates of aquatic organisms, including bacteria, which often grow more rapidly in warmer waters.
• It can affect the sensitivity of organisms to toxic wastes, parasites, and diseases.
• It can indicate the presence of thermal pollution, such as from cooling water effluent or warmer water from a tributary.

By regularly testing water temperature and understanding its implications, we can better manage and protect our water ecosystems.

pH testing

Testing the pH of a water sample is one of the most common water quality tests performed. The pH level is a measure of how acidic or alkaline water is, and it is indicated on a scale from 0 to 14, with 7 being neutral. A pH reading below 7 indicates acidity, while a reading above 7 is alkaline or basic.

The pH level of water is important for several reasons. Firstly, it affects water quality, which is crucial for all living things, agriculture, and recreation. Secondly, it can indicate the presence of pollutants. For example, a change in the pH level of a stream can signal increasing pollution or some other environmental factor.

Water with a pH level below 7 is acidic, which means that toxic heavy metals, such as iron, manganese, copper, and lead, can easily dissolve in it. These metals can then leach into drinking water from pipes or the local aquifer. Iron causes a metallic taste and reddish stains on clothing and plumbing, while other metals like lead are toxic.

On the other hand, water with a pH level above 7 is alkaline or "hard" water. This type of water contains excess minerals like calcium, which can cause scaly deposits on cookware and a bitter taste in coffee.

There are several methods to test the pH level of water:

• PH Meter: This is a small, portable device used by scientists to measure pH levels in water. It can be used on-site or in a laboratory. The meter has a cup that holds the water sample and a glass probe with two specialised electrodes. The pH electrode measures the acidity of the water, while the reference electrode is immersed in a liquid with a fixed acidity. The meter then converts the voltage difference into a pH level.
• Test Strips: These are small, single-use strips that change colour to indicate the pH level of the water. The user dips the strip into the water sample and then compares the colour of the strip to a colour chart to determine the pH level.
• Colour Disk Kits: For this method, the user adds a powder packet or a few drops of a liquid reagent to a water sample in a reusable plastic tube. The sample tube is then placed in a small plastic viewing box with a colour gradient disk inside. The user rotates the disk to match the colour of the sample and reads the pH level from the disk.
• Hand-held Digital Instruments: These lightweight and portable devices, such as digital meters, colourimeters, and photometers, provide accurate pH readings. They require batteries and calibration and are commonly used by field technicians.

It is important to test the pH level of water regularly, especially if there are potential pollution sources nearby, to ensure that the water is safe for drinking, agriculture, and recreational use.

Testing for dissolved oxygen

There are several methods for testing DO levels, including chemical analysis and modern techniques using electrochemical or optical sensors. Here are the key methods:

Winkler Titration Method

The Winkler method is a widely used chemical analysis technique that provides a "one-time measurement" of DO. It involves collecting water samples, fixing them with reagents, and then titrating them in a laboratory setting or in the field. This method requires immediate fixation of the samples as atmospheric contact and agitation can impact DO levels. The Winkler method is known for its accuracy, but it is also associated with concerns about inaccuracies, sample contamination, and human error.

Electroanalytical Method (Galvanic and Polarographic Probes)

The electroanalytical method is commonly used in laboratories and field testing. It employs electrochemical dissolved oxygen sensors, also known as amperometric or Clark-type sensors. There are two types of electroanalytical sensors: galvanic and polarographic probes, which operate based on redox (oxidation-reduction) reactions. These probes provide continuous and live measurements of DO levels. Both types of probes require a "warm-up time" for the electrodes to polarize before taking measurements.

Optical Dissolved Oxygen Method

The optical dissolved oxygen method uses a probe with a semi-permeable membrane to monitor luminescence instead of a chemical reaction. These probes emit blue light, which excites light-sensitive material inside the probe cap. When the material returns to its normal energy state, it emits red light that is measured by a light sensor inside the probe. The presence of DO suppresses the red light, altering its frequency, intensity, and decay. While this method provides continuous DO measurements, it can be influenced by humidity.

Colorimetric Method

The colorimetric method is a chemical analysis technique that involves adding chemical reagents to water samples, causing them to display a specific colour. The intensity of the colour is proportional to the DO concentration in the sample. This method is typically used to measure DO concentrations between 0.2 and 15 ppm, and it is unaffected by salinity, temperature, or dissolved gases. However, certain substances like ferric iron, nitrate, and sodium sulfate can interfere with the results.

Turbidity testing

Turbidity is measured in nephelometric turbidity units (NTU). The Environmental Protection Agency (EPA) requires that 95% of drinking water in one month has a 0.5 NTU or less turbidity reading. Samples may not be higher than 5 NTU at any time.

There are several ways to test the turbidity of water. One method is to use a turbidity sensor, which emits infra-red light into the sample and measures the incident light scattered at right angles from the particles in the sample. This technique is in accordance with ISO 7027 and uses Formazin as a reference standard. The turbidity is displayed in Nephelometric Turbidity Units (NTU), which are nominally equivalent to Formazin Turbidity Units (FTU).

Another method to test the turbidity of water is by using a spectrophotometer. This machine shines a light through the sample and measures the amount of light that is scattered and reflected back to the sensor to determine the turbidity. The more light that is scattered and reflected, the higher the turbidity.

Testing for turbidity is important because it can indicate the presence of pollutants and contaminants in the water, such as metals and bacteria, which can be harmful to aquatic life and human health. Additionally, sudden changes in turbidity may indicate the emergence of a new pollution source or an issue in the treatment process for drinking water.

Chloride testing

Chloride is a negatively charged ion formed when chlorine gains an extra electron. It is commonly found in the form of salts, most often sodium and potassium salts, which are highly soluble in water. Chloride is present in rainwater, streams, groundwater, seawater, wastewater, and urban runoff. It is also used in water treatment chemicals, de-icing agents, and as a fertiliser.

High levels of chloride in water can cause several issues. It can corrode and weaken metal piping and fixtures, giving drinking water an unpleasant "salty" taste. It can also damage household appliances, boilers, and irrigation systems by inhibiting the growth of vegetation. In concrete structures, high levels of chloride can corrode the metal reinforcements.

There are several methods to test for chloride in water. One way is to use test strips, which are small, single-use strips that change colour to indicate the concentration of a specific chemical. Another method is to use colour disk test kits, where you add a powder packet or a few drops of a liquid reagent to a water sample in a reusable plastic tube, then place it in a small plastic viewing box to compare the colour of the sample to a colour gradient. More advanced methods include using hand-held digital instruments such as lightweight and portable digital meters, colorimeters, and photometers, which provide more accurate results but are more expensive and delicate.

When testing for chloride, it is important to consider the potential sources of contamination and the possible effects on the water. While chloride itself may not be harmful, it can indicate the presence of other contaminants that could be harmful. Additionally, elevated levels of chloride can have indirect health risks, such as exposure to corrosion by-products like copper and lead. Therefore, it is recommended to compile information about the water source, well construction, surrounding land use, and local geology to identify potential sources of contamination.

Frequently asked questions