How to Remove Tannin From Water

Robert Paxton

Tannins are organic materials that naturally occur in the soil and can pass into groundwater sources. They tend to discolor water and give it a bitter taste. They are not toxic and are harmless to humans. However, their presence can make well water unpleasant to drink and can even stain laundry.

Tannins are not a health hazard but can give drinking water a bad taste.

For this reason, people seek to treat their water supply for this problem.

  1. Insert an anion exchange device into your water supply. These devices function like water softeners. They contain minerals, such as rock salt, which react with the tannins, removing them from the water supply as they aggregate with the minerals. These devices can affect the levels of chloride, sulfates and alkaline in your water and must be carefully monitored.

  2. Add an iron filter to your water system. Tannins often appear with iron and other metals in water. These particles also discolor the water supply. A good iron filter will simultaneously remove tannins, especially if the water has been pretreated with chlorine or ozone. Sometimes tannins will coat the surface of these filters, rendering them useless, so they too must be closely watched.

  3. Inject a flocculant into your water supply's holding tank. A flocculant is a liquid that will remove the positive charge of the ions in tannins and allow them to flock together and settle at the bottom of the tank. This sediment can later be removed. Using a filter in tandem with this device will guarantee that any particles that manage to remain suspended will be removed from the water.

  4. Order an ultrafiltration membrane to install in your water system. These devices filter bacteria and iron, soften water and remove tannins. Installation may require occasional addition of sodium or potassium tablets.

  5. Pretreat the water with chlorine and install a backwash sediment filter. This device can capture and remove particles as small as 5 microns. Sediment is regularly backwashed out of the system so as not to later contaminate the water supply.