Water Quality Testing Indicators FAQ

Water Quality Testing Indicators

Regular testing water for drinking, swimming and pool care is important. When large amounts of water sit in one place for too long, the risk for contamination will increase. Make sure you are always using the safest, cleanest water in your home and pool by following our handy FAQ guide for water testing:

What is water sampling or testing?

Water sampling describes the process of testing and analyzing a volume of water in your taps or swimming pool to ensure that it does not contain any pollutants.

What is free chlorine?

Free chlorine is the chlorine available to disinfect the water in your home or pool. It kills off bacteria by combining with contaminants to form what is known as combined chlorine or chloramines.

What is combined chlorine?

Combine chlorine is formed when the free chlorine reacts with the contaminants in the water. It is essentially “used up” free chlorine and can no longer disinfect the water.

What is total chlorine?

Total chlorine is the combination of both free and combined chlorine. A total chlorine test determines the total amount of chlorine that exists in the water.

What should I be testing for?

It is recommended to test for both free and total chlorine regularly so you can make sure you’re adding the right amount of disinfectant to treat the water. The four main tests you can do are for the chlorine, PH, total alkalinity and calcium hardness levels.

How often should I be testing the water?

Drinking water should be tested at least once a year. If you are swimming in your pool a lot, it is a good idea to check the chlorine levels of the pool every day or at least two or three times a week. It is also recommended to test the water again after heavy rainfall and 24 – 48 hours after chemicals have been added. You can check for calcium hardness and Cyanuric acid less frequently – approximately once a month.

How can I test the water?

It’s easy to test the chlorine levels in your water by using either a chlorine comparator or a photometric instrument. These tests contain a substance that reacts with the water and shows up as red when chlorine is indicated.

When should I “shock” my pool?

If the level of total chlorine is higher than the free chlorine or your pool has a strong or strange odour, you may have to shock the pool to remove the excess total chlorine.

How do I decrease the free chlorine level if it’s too high?

To lower the level of free chlorine in your water, you can partially drain the pool and re-fill it. Alternatively, you can add sodium thiosulfate to decrease it. Exposure to the sun will also help to reduce the levels of free chlorine.

What are pH levels?

The pH level is the amount of acidic compounds in the water. pH levels can be affected by rainfall, dirt, excessive chemicals and lack of exposure to the sun.

What is total alkalinity?

The total alkalinity levels are the amount of alkaline substances in your water.

What is Cyanuric acid?

Cyanuric acid is a stabiliser or conditioner for your pool. It protects the chlorine from reacting to the sun’s UV rays.

What is total hardness?

The total hardness in your pool describes the amount of calcium or magnesium that exists in your water. When the total hardness is too high, scale can form on the walls of the pool and make the water appear murky.

How can I get rid of algae?

Algae is a made up of tiny microscopic plants that grow in the water of your pool. They form from organic matter such as leaves and plants or even from organisms left by swimmers. Algae growth is exacerbated by low chlorine levels, high volume of phosphates, pool filtration and circulation and incorrect pH levels, amongst other reasons.

How do I get rid of algae in my pool?

The way you treat the algae depends on the type of algae that exists in your pool – whether it is black, green or yellow. Most of these types of algae can be removed with algaecide or a shock treatment.

What are phosphates?

Phosphates are one of the main sources of nutrients for algae and can reach your pool through leaves or grass, animals, precipitation or through your tap or hose pipe.

What are the recommended levels for testing?

  • pH: 7.2 – 7.8
  • Chlorine: 1.0 – 2.0 ppm
  • Total Alkalinity: 80 – 120 ppm
  • Calcium Hardness: 200 – 400 ppm
  • Cyanuric Acid: 20 – 50 ppm
  • Total Dissolved Solids: below 5000 ppm

It is important to test your water regularly so you can be sure you are drinking and swimming in water that is safe.

Photo Credit: Weidner on Flickr


About the Author:

Lauren Morling
Lauren Morling is a South African freelance writer living in London. She has a passion for digital marketing and has been published in The Touristin, a Luxury Travel Blog, Life As a Human and the Daily Mail. Lauren works in digital marketing and has a journalism degree from the University of Cape Town.

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