pH Testing

pH is important to monitor and control in drinking water as it can directly affect the performance of the treatment and disinfection process. The WHO state that the pH will vary in different supplies according to the composition of the water and the construction materials used in the distribution system. According to the WHO for effective disinfection with chlorine, the pH should be less than 8.0.

The US EPA consider pH of drinking water a secondary contaminant as it does not have a direct impact on health. According to their Secondary Standards, pH in drinking water should be between 6.5 – 8.5. A low pH can result in bitter, metallic tasting water and can cause corrosion of pipes. Whereas, a high pH can cause water to have a soda like taste.

The DWI include pH as an indicator parameter. They specify that the pH of drinking water should be between 6.5 and 9.0.

pH is a critical parameter in aquaculture as most forms of aquatic life are very sensitive to pH changes. Consistent high or low pH levels will negatively impact the growth and reproduction abilities of fish.

Changes in pH can also affect aquatic life indirectly by altering other aspects of the water chemistry. At a high pH most ammonium is converted to toxic ammonia (NH₃) which can kill fish. For more information about test parameters in aquaculture take a look at our case study on Water Testing at London Zoo.

pH of wastewater has a direct influence on water treatability; it must be monitored because the bacteria are highly sensitive to drops in pH. It must also be controlled to protect equipment from corrosion.

It is necessary to control the pH of wastewater to protect the environment; the discharged waters will affect the receiving source. The typical consent limit for pH of discharge waters is between 6 and 9.

pH is a fundamental parameter in pool and spa testing. Maintaining the right pH, ensures the effectiveness of chlorine and helps to protect pool fittings against corrosion.

Ideally in pools and spas pH should be maintained between 7.2-7.4. This allows for effective disinfection and is optimal for bather comfort. An overall range of 7.0–7.6 is acceptable in most pools. pH should be measured daily and should always be measured at the same time as the disinfectant.

For an overview of key testing parameters, guidance on recommended levels and the effects of poor water monitoring download our pool chemistry guide or spa chemistry guide.

pH is a critical parameter for healthy plant growth and crop yield. The optimum pH for most home gardens is around 6.5 as most plants thrive in the 6.0-7.0 range. However, some plants, such as blueberries and azaleas, prefer more acidic soil, and few, such as ferns and asparagus, do better in slightly alkaline soil.

In the 6.0-7.0 range the availability of major nutrients is at its highest and bacterial and earthworm activity is optimised. A too high/low pH often wont kill plants outright but it can affect their growth and result in poor crop yields.