Iron is a naturally occurring mineral found in water especially groundwater which has come in contact with iron-containing rock or soil. Insoluble iron can clog valves and strainers and can cause excessive sludge build up in low lying areas of a water system. It also leads to boiler deposits that can cause tube failure. Suspended or dissolved iron coming in the feed water will also deposit on the boiler metal. Checking iron in boiler and cooling water helps to monitor corrosion level in water. AQUASOL AE303 - IRON TEST KIT iron test kit gives a clear red colour result which is then compared with the colour chart provided.