Taming Tannins: The Secrets to Crisp and Clean Water

Water Quality | August 23, 2023

Ever wondered why your bath or toilet water sometimes looks a bit off-colour? It might actually be a substance called Tannins in the water. Tannins are natural substances that come from the way water interacts with soil and decaying plants. This can make the water look a little yellow or even like tea. Sometimes, when these tannins mix with iron in the water, they can cause yellow stains on clothes, fixtures, and other things. Tannins can also give water a slightly tangy taste and a kind of earthy smell. These tannins are more common in water from marshy or coastal areas.

What Do Tannins Do to Your Health?

Don’t worry too much about tannins when it comes to your health. They’re mostly about how the water looks and tastes, not about making you sick.

Should You Test Your Water for Tannins?

A simple test involves filling a clear glass with water and allowing it to sit overnight. If the colour settles at the glass bottom, the discoloration is likely caused by iron and manganese, not tannins. If the colour remains consistent, it’s more likely due to tannins. If you suspect tannin presence in your water and want to quantify the amount, you can have your water tested for tannins at our EDS Pumps lab. It’s also recommended to test for sulphates, alkalinity, iron, total dissolved solids (TDS), and hardness, as these factors can help determine the most effective treatment approach. Testing for iron alongside tannins is important because iron can produce a false positive for tannins, requiring adjustment for accurate tannin concentration assessment.

How can you remove tannins from your water?

A common method for tannin removal involves using an organic scavenging anion exchange resin. Depending on the type and concentration of Tannin you have, you may also need a water softener as a pretreatment, which enhances the resin’s longevity and tannin absorption capacity. Periodic regeneration of the anion exchange resin with a soda ash and saltwater solution is recommended for optimal performance. Oxidation and filtration are alternative methods for tannin removal, but they are more complex than anion exchange and softening. It’s worth noting that tannins might interfere with equipment utilized for treating other water issues, such as iron filters or neutralizing filters. At EDS, we assess tannin levels before installing such water treatment systems. Feel free to reach out to our Certified Water Specialists if you have inquiries about tannins or any other water treatment matters.

David Mellis

President at EDS Pumps & Water Treatment Ltd

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