Southwest Metropolitan Water and Sanitation District experienced 20 water main breaks in 2019, costing the district nearly $280,000. Almost half of these failures were caused by electrolysis corrosion and occurred on cast iron and ductile iron pipe aged 35 to 50 years old.
Electrolysis corrosion of buried iron is caused by the discharge of electric current that has entered the pipe from an outside source. Also referred to as Galvanic Action, this process causes loss of pipe wall integrity, ultimately resulting in a water main failure.
Some of the 2019 failures were on cement water mains that occurred after sewer service line replacements. Backfilling of the trench can pose extreme stress on the water main, which in turn, causes it to fail.
As the assets of the District age, the need for maintenance of existing facilities and replacement of other assets increases. In 2014, the District Board of Directors imposed a $1.00 per month water and sewer service fee on all District Customers. Over the past few years, the surcharge has been gradually raised each year to match operating expenses, emergency repairs, and projected capital expenditures. The current Service Fee is $8.00 per ¾ inch equivalent.