In humid summer weather, infrequent use and moisture often cause water to accumulate in residential oil tanks. This can lead to rust, damage moving parts, and form a breeding ground for bacteria that can deposit harmful sludge at the bottom of the tank. Fortunately, it’s possible to remove this excess moisture before a costly replacement is necessary. If you're concerned about water getting into your tank, here's a closer look at how to address this problem.

How Water Enters Oil Tanks

The two most likely causes of water in an oil tank are condensation and rain. Residential oil tanks are equipped with air vents that admit air to relieve the vacuum created when oil is consumed. Moist air contains trace amounts of moisture that will condense and form droplets inside the tank when heated under summer temperatures.

Although oil tanks are tightly sealed to block out rainwater, they’re still exposed to the elements at all times. Rainwater can enter the tank through openings like fill points or damaged vents, seals, filler caps, and cracks in the tank walls.

How to Check for Water

Water is less dense than oil, so droplets will settle to the bottom of your tank soon after they form. Simply looking at the top of the tank often won’t alert you to the presence of moisture. 

The simplest and most reliable method of testing for water is by smearing a water-finding paste on a string or stick and lowering it to the bottom of the tank. This substance will change color upon contacting water, with different shades or intensities of color indicating the amount present.

How to Remove Water

How you remove water will depend on the material of your residential oil tank. A metal tank will have a sludge valve that will drain out most of the water and small amounts of oil when you open it. This mixture should be captured in a sealable plastic container and disposed of at a waste disposal center.

Plastic tanks don’t have sludge valves and must instead be pumped manually. This is only effective for small amounts of water, so if you have a more serious problem, it’s necessary to turn to a professional for assistance.

If you’re concerned about water posing a risk to your residential oil tank, contact Andersen Oil Company in Ledyard, CT. They have over 45 years of experience serving households throughout New London County and the southeastern part of the state. In addition to regular deliveries, they offer comprehensive emergency services and maintenance plans to keep your system in peak condition year-round. Call (860) 464-7628 to discuss your needs, or visit their website to learn more about their services.