A good way to monitor the level of your oil for leaks is by using an oil gauge or oil monitor. This will tell you is there is a sudden loss of oil or a slow leak in your oil tank as well as monitoring your heating oil usage and alerting you when the tank needs to be refilled.

If water is present, it can be pumped out by using a small hand pump.  Once the water is removed, it would be advisable to flush the boiler feed pipe and change the oil filter to ensure all water is removed.  Depending on your skills, this is probably an operation that should be carried by a service engineer.

The principal sources of water in oil storage tanks are rainwater and condensation.  Rainwater can enter a tank if openings in the tank are left exposed, seals are faulty or damaged or the integrity of the tank has been compromised by rusting or by perforations, cracks or splits in the body of the tank.  Condensation will often occur naturally as the result of temperature differences between the tank/oil and the surroundings, It is part of a delivery driver’s training to ensure that all of the openings used when filling a tank and gauging its contents are closed securely after the filling operation has been completed.