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Fact Sheet Coliform bacteria in a water system are generally either a result of a failure to maintain a "closed" water system and/or a treatment failure. Visually inspect the system for "openings" and/or treatment equipment failures. Look for areas of the system where soil, leaves, insects, birds, sewage, or animal wastes could possibly get into your water system. Check the following: WELLS Well casing is above the floor or ground and the area around the well is clean. Well has a watertight seal and has a U-shaped, inverted, screened (minimum 24-mesh) vent. There are no openings in the well cap or casing, including around the electrical wires. There is no standing water around the source. The well is at least 100 feet from sources of contamination, such as septic tanks, drain fields, sewers, manure, or garbage. The well has been effectively disinfected following any well or pump repairs. A dug well has a watertight lid with overhanging edge and a neoprene-type seal between the lid and the well casing. SPRINGS The collection box and the hatch or lid are watertight. The hatch should have an overhanging edge and a neoprene-type seal. Vents are covered with an insect-proof non-corroding screen (minimum 24-mesh). Overflow and drain lines are screened or protected with an angle-flap valve. Surface water is directed away from the spring collection area by a diversion ditch. The spring is at least 200 feet from sources of contamination, such as septic tanks, drain fields, sewers, manure, or garbage. TREATMENT Chlorine residual is measured and levels are adequate. UV system is operating correctly. August 2010 DOH 331-180 (Updated) Troubleshooting Checklist for Coliform Contamination ---PAGE BREAK--- If you need this publication in an alternate format, call (800) 525-0127. For TTY/TDD, call (877) 833-6341. HYDROPNEUMATIC and BLADDER TANKS Tank(s) are not waterlogged. Sediment has not accumulated in the tank. Bladders are intact and functional. RESERVOIRS and STORAGE TANKS There are no openings that allow entry of surface water, debris, insects, etc. The access hatch has an overlapping, watertight cover and a neoprene-type seal. Vents are clean, directed downward, and screened (minimum 24-mesh). Overflow and drain lines are protected with screens or angle-flap valves and discharge above ground. The drainpipe should not be submerged in nonpotable water. There are no signs of dirt, insects, growth, sediment, or debris inside the tank. There are no cracks, leaks, or vegetative growth on the outside of the tank. DISTRIBUTION SYSTEM There are no obvious leaks or breaks. The system has been effectively disinfected following any construction or repair work. There have been no low pressure or water outage incidents. Non-looped, dead-end sections are regularly flushed. System is free of possible cross connections. AFTER INSPECTING SYSTEM Make needed repairs and improvements. Disinfect and flush the system according to DOH guidelines. Install sample taps at source and storage facilities, if needed. Establish or improve preventative maintenance program (routine sanitary control area inspection, storage tank inspection, and distribution system flushing). FOR MORE INFORMATION Contact our regional office: Eastern Region: Spokane Valley (509) 329-2100 Northwest Region: Kent (253) 395-6750 Southwest Region: Tumwater (360) 236-3030