How do you eliminate the midge-fly larva bloodworm from potable water treatment and distribution systems?

Answer 1

You go two place you need to look.

1) you reservoirs. Check for breaches, openings that insects could enter the tank. Check you screens on your tanks. Move towards a window screen sized aluminum mesh. Climb your tanks monthly and make sure the screens are intake. If you have live worm is in your distribution system and you have no chlorine residual. Which maybe an even bigger problem.

2) your filters. All filters are biologically active. Your filter maybe infested with the larva. Increase you backwashing with a chlorinated 1.5-2 ppm and backflow rate of 20-23 gpm/sq ft. BW three times in succession.

3) If you have larva/worms in your tank. Remove the tank from service and steam clean it. If the tank can not be removed from service hire a potable water diving contractor to remove all loose sediment from the floor of the facility then do a chlorine burn.

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Additionally to reduce infestation at the filters Don't turn on plant lighting until 45-minutes after sunset. The midges are attracted to light. after 45 minutes they are going somewhere else.

Prevention

Houses and buildings with outside lighting will attract large numbers of non-biting midges. Move light away from sensitive areas such as doorways, windows, patios, etc. Avoid the use of unnecessary lights until 45 minutes after sundown since 90 percent or more of flight activity takes place before that time. Sometimes, eggs are laid on surfaces around lights and on buildings. These egg masses can become unsightly and smear when wet. By replacing a 100-Watt Mercury vapor light (ultraviolet energy) with a 50-Watt high-pressure sodium vapor light, midge concentrations are significantly reduced. (Lights least attractive to insects are sodium vapor or halogen with pink, yellow or orange tints and dichrom yellow bulbs.)