Colour in waters are normally due to Iron and Manganese or Organic Tannins ( often from Peaty Water ). If the colour is due to Tannins the colour may be reduced by specialised ion exchange resins.

Colour in water ( after it has been filtered ) is typically caused by both Iron and Manganese compounds or by Organic compounds. If the colour is due to Iron and Manganese there are specific treatments for this. If the colour is due to Organics then treatment is normally by Ion Exchange or Activated Carbon.

Organic colour originates from decaying vegetation and may be completely soluble or particulate. Tannins ( Humic and Fumic acids ) are by far the most common class of compounds and give the water a yellow / brown tint. On moorlands ares such as the Highlands in Scotland where water runs off peat the water can be very dark brown.

Ion Exchange :- Water passing thorough anion resin beads is bound to the resin by the action of adsorption. When the resin becomes saturated and can hold no more colour forming compounds they are required to be removed. Resin selection is important and of the various types some use caustics to remove organics and there are some which utilise salt regenerating with brine, or a combination of the two. Flowrates are reasonably fast and the colour removal approximately 2000 mg/l per 25 litre of resin before regeneration required.

Activated Carbon :- this absorbs the organic colour. These systems are very good where the colour levels are low or volume capacity low and ideal as a polishing final treatment. Once exhausted the carbon is discarded and replaced with new.

The Organic Scavenger and colour removal works by ion exchange and a system not unlike a water softener is used. A valve atop a pressure vessel filled with resin allows the water to flow through before becoming exhausted and the resin refreshed. This is done by salt in a brine solution and sent to drain as waste. It may be done with a timeclock or water meter controller.