What caused pipes to leak under hundreds of Folsom homes? We may finally have an answer

For months, leaks have been springing in the pipes under homes in Folsom, causing costly repairs for hundreds of homeowners. City officials think they may have finally found a culprit: Folsom’s water is just so pure.

“The City has produced a high-quality potable water that under most circumstances provided the optimal corrosion control treatment as demonstrated by historical compliance with the (EPA’s Lead and Copper Rule),” a city report issued this week said. “However, the purity of this water source resulted in a rare set of conditions that can contribute to pitting conditions in copper pipe.”

Drawing its water from the snow melt collected from the Sierra Nevada, Folsom has a uniquely pure water source. So pure, in fact, that it is devoid of many minerals that are important to maintain a neutral pH while it is pumped through copper pipes.

The lack of minerals can cause the water to act “aggressively” toward metallic pipes, according to a report prepared by Black and Veatch, a Rancho Cordova-based consulting company. The water tries to pull minerals from its surroundings to neutralize, but damages the pipes in the process.

Since July, Folsom residents have reported over 1,000 pinhole leaks in the copper pipes that feed water from the treatment plant to homes stretching from American River Canyon to Empire Ranch.

The leaks, the report found, are likely a result of corrosion pits, which are a weakening of the pipes in areas where the water reacts with impurities or sediment, stripping pipes down to the copper ions.

To manage the water’s natural corrosive tendency, the city’s water treatment plant adds lime to stabilize the water’s pH, alkalinity and calcium. And, as the report says, Folsom has been largely successful in managing the water’s pH.

But since 2017, daily fluctuations in the water’s pH have become more pronounced and have increased slightly – just enough to potentially be the source of the corrosion.

The water’s pH often varies by season, but data in the report shows the pH reached 9.0 in much of 2019 and 2020, which combined with the low alkalinity of the pure water and chlorine as a disinfectant could have created the conditions that led to pinhole leaks.

Images of the pitting included in the report showed small, blue spots scattered like chicken pox through a dissected section of pipe.

Pipe leaks in Folsom homes

Paula Mays, a Folsom resident, said she has had four leaks in six months at her home. The first leak appeared on April 12 – Easter Sunday – in the garage. A plumber had to cut through the drywall to fix it, but it was still a “pretty easy fix,” she said.

But a week later, she and her husband heard water running through the walls of their entryway closet, and the travertine flooring felt very hot. This time, the plumber had to jackhammer through their tile entryway for two days to get to the leak in a hot water pipe. At one point, the floor reached 110 degrees, destroying much of the adjacent flooring, too.

Five days after that, they found another leak a few feet away under the ceramic tile floor and they had to jackhammer the floor again. It took two weeks to pump the water out, she said. The slab was so wet that it soaked the carpet in three bedrooms, requiring another replacement. During this repair, she and her husband had to move out of their home and live in a hotel for three weeks.

“We’re really pretty laid back people,” she said in a phone interview. “We thought we’ll just get it done, move forward and try to keep a positive attitude. But there were a couple days there where I was about ready to lose it.”

When a fourth leak was found, the couple decided to finally spend $20,000 on new plumbing in their home. In all, she said they spent more than $40,000 repairing their home, and insurance only covered the first leak.

“It’s a moment in time, and we’ll just get through it, believe me,” she said. “I’d like to have the money back but I don’t think that’s going to happen.”

Four of her neighbors have experienced leaks, but not as serious.

One of her neighbors sold their house and moved out of Folsom after repairing their first leak, she said.

To help slow the pitting, the city has added orthophosphate to the water treatment, an EPA-approved chemical which is added to water systems to help delay the corrosion of metal pipes. It is safe to drink.

“The use of orthophosphate has been shown to inhibit pitting in aggressive waters by hindering pit initiation ... and it can help to slow or even mitigate pit propagation on pits that are already initiated,” the report said.

It’s unclear what effect the addition of orthophosphate has had so far in slowing the pinhole leaks.

This story was originally published October 21, 2020 at 5:00 AM with the headline "What caused pipes to leak under hundreds of Folsom homes? We may finally have an answer."