Why pesticides in wastewater are a problem Traces of certain synthetic pesticides periodically have been getting into Fort Worth's sewer system, going through the treatment plant and into the Trinity River. Test failures have been linked to diazinon or its breakdown products, but high levels of malathion have been detected occasionally. The Village Creek Wastewater Treatment Plant is an award-winning facility, but it was never designed to remove pesticides.
Rain washes freshly applied pesticides from lawns into sewer manholes or open drain cleanouts.
Pesticides fall onto pavement during application where they can be washed into the sewer system. Garments or rags with pesticides on them are washed in the washing machine. People pour leftover pesticides down the bathtub, commode, sink, sewer line cleanout or floor drain. People use the tub or sink to dip their pet for fleas or ticks and then release the dip water down the drain. The only guaranteed way to keep synthetic pesticides out of the sewer system is for residents to stop using diazinon and decrease the use of other pesticides.