Investing in water storage: tank upgrades and maintenance
Sonoma Water maintains 18 water storage tanks as part of its water transmission system. To ensure their longevity and resilience, these tanks are undergoing a 10-year, $80 million project focused on long-overdue recoating and seismic retrofits.
One of the latest completed projects is the Kastania Tank in south Petaluma, which holds 12 million gallons of water. It was returned to service in September 2024 after undergoing a full recoating, requiring 6,850 gallons of paint—enough to cover a typical 1,500-square-foot home 250 times!
Currently, the six-million-gallon Cotati Tank #1 is in the final stages of a similar recoating process. Next in line is Cotati Tank #3, the largest in our system, with an 18-million-gallon capacity. This tank will be out of service for much of the year as it undergoes a comprehensive overhaul, including interior and exterior recoating, corrosion protection, seismic retrofitting, and other critical upgrades.
The tanks are an important safeguard for our water system for times of emergency. Sonoma Water manages and maintains 109 miles of aqueduct with 18 storage tanks that can hold up to 128 million gallons of water when all are in full operation. To ensure an adequate water supply,
pressure, fire flow, and emergency storage, Sonoma Water strives to maintain an average of 100 million gallons of water.
The actual water storage at any given time fluctuates based on factors such as water demand and the status of tanks that may be offline for maintenance, repairs, inspections or upgrades. Sonoma Water carefully balances the need to take tanks offline for essential upkeep with the ongoing demand for water, ensuring a reliable supply for both routine operations and emergency situations.
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