Checking basement tanks for the presence
of water presents a unique set of challenges. In
some cases the tank is not pitched towards the
bottom fitting and in other cases this fitting was
plugged at the time of installation.
Tank top component removal to facilitate
tank gauging should only be undertaken when
evidence exists that water may be present
(excess water in the filter, rust in pump cover
or filter canister, etc.). Removal of tank top
fittings requires those fittings be properly
sealed after the gauging is completed to assure
tank integrity is maintained.
When checking any tank for water, the
burner should be off. Water finding paste
should be applied to the bottom several inches
of the side of a tank gauge stick adjacent to
the side with the measurement increments
embossed. Whenever possible, a non-folding
gauge stick should be used. Fully insert the
gauge stick into the tank until it touches the
bottom. Leave the stick at the bottom for
about 30 seconds. If water is present, the paste
changes color to the height of the accumulated
water.
When trace amounts of water are detected,
complete removal may be impossible, but
every effort should be made to reduce the level.
6 National Oilheat Research Alliance
Much of the focus with water in the tank has
been on condensation. However, anytime water
is identified in a tank it is important to inspect
the tank system, identify any means of water
entry and advise the customer of recommended
repairs.
Pumping out the water doesn’t correct
the situation, it merely treats the symptom.
Sometimes, accumulated water is the result of
other problems with the tank or its components.
When a measurable amount of water is
identified, it should be removed, the source
determined, and the problem corrected so that a
reoccurrence is prevented.
External Corrosion is the main cause of
failure of unprotected USTs. It occurs when
the moisture and oxygen in the soil around the
tank, along with other elements in the soil, lead
to corrosion of the tank.
ASTs are also subject to external corrosion
due to contact with walls, structures, soil,
organic matter, etc. Manufacturers' instructions
provide valuable information regarding tank
placement and recommended maintenance.
Fills that are flush to the ground, fills with missing caps,
broken tank gauges and vials are among the common
causes of water entry. These situations should be
corrected to ensure a watertight seal.
All the paste has changed color indicating that the
water level may be higher than indicated. Paste
should be cleaned off and reapplied to a higher level to
determine the actual level of water in the tank.