Water, Water, Everywhere, But Why’s It In My Tank?

Water, Water, Everywhere, But Why’s It In My Tank?

By Wally Jemmings

When DEQ is informed of water in an underground storage tank, the reaction as regulators is, “OH NO!  SUSPECT RELEASE! SHUT IT DOWN! PUMP IT OUT! CALL THE LEAK HOTLINE! CALL THE DISASTER AND EMERGENCY SERVICES DUTY OFFICER! CALL EVERYBODY!” However, while tank owners are required to report any unexplained presence of water in tanks or interstitial spaces, there are other ways water can enter an underground storage tank that have nothing to do with a breach in the tank or a release of fuel to the environment. 

As you can imagine, an underground storage tank containing fuel that will end up in a car engine is not a good thing. Sure signs that there is water in a tank include: dispensers that flow at half their normal rate due to clogged filters; meter failure; visible rust; microbial slime; excessive system maintenance and filter replacement; ATG water warnings and alarms; and of course – customer complaints. 


Checking for water in your tanks regularly and immediately removing it is critical to the operation and maintenance of your system.  Industry experts suggest checking for water anywhere from before and after each delivery, to once every 30 days. It is recommended that both ends of the tank are checked and the product is periodically sampled.  EPA recommends visually inspecting tanks, not just from the surface, but by internally inspecting tanks with photos, videos, or manned access.  It is important to remember that any unexplained presence of water in your tank or interstitial space is considered an unusual operating condition and must be reported to the department within 24 hours.


So how bad is it to have a little bit of water in your tank? Corrosion-inducing microorganisms need water to survive. Once established in a tank, these microorganisms can be very destructive and difficult to remove. In July 2016, EPA released Investigation of Corrosion-Influencing Factors In Underground Storage Tanks With Diesel Service. The investigation included the inspection of 42 steel and fiberglass underground storage tanks to find out which components of the systems were most susceptible to corrosion and what was causing it. One of the most eye-opening conclusions of the study was that metal parts are corroding and owners don’t even know it!


There are several ways that water can get into a tank.  Other than a hole in your tank, water can accumulate from condensation inside the tank, tank-top access points that are not tight, water in the fuel distribution system, and water in the delivery truck. In order to help prevent water from entering your tank, remove standing water, ice, and snow from around all tank riser covers and sump lids, make sure all tank-top access points are tight, keep spill buckets clean and dry, and keep tanks as full as possible to avoid excessive condensation. 


If you find water in your tank, contact your local service provider to have it removed immediately, and then determine where the water is coming from.  Remember, any unexplained presence of water in your tank or interstitial space is considered an unusual operating condition and must be reported to the department within 24 hours. If you discover signs of corrosion, the entire tank system should be investigated. The effects of corrosion can be seen on submersible turbine pump shafts, flapper valves, ball float vent valves, and other tank components that can be difficult to see from ground level. Corrosion on overfill prevention devices and leak detectors can leave your system vulnerable. They may not operate as designed and could cause a release to the environment.


Due to the changing chemistry of newer fuels, keeping water out of your underground storage tank is more important than ever before.  If there’s water in your tank, remove it. When you find out where the water is coming from, fix it. If you don’t know where it’s coming from, report it! There are plenty of online resources available to help tank owners properly operate and maintain their tank systems, some of which are listed here: 










In the words of Benjamin Franklin, “In wine there is wisdom, in beer there is Freedom, in water there is bacteria.” 




Amiee Reynolds (Bureau Chief): 444-6435                  

Contaminated Site Cleanup Bureau

Amy Steinmetz (Section Supervisor): 444-6781      

Petroleum Tank Cleanup Section                  

Federal Facilities and Brownfields

Leanne Hackney (Program Manager): 444-0485         

Underground Storage Tanks Program

Terry Wadsworth (Executive Director): 444-9712        

 Petroleum Tank Release Cleanup

Jeni Garcin (Public Information Officer): 444-6469       

Directors Office

Underground Storage Tanks
1520 East Sixth Avenue | Helena, MT 59602-0901
Phone: 406-444-5530 | Fax: 406-444-1374
Email: dequstprogram@mt.gov | UST Web: http://deq.mt.gov/Land/ust

Petroleum Tank Cleanup Section Federal Facilities and Brownfields
1225 Cedar Street | P.O. Box 200901 | Helena, MT 59601
Phone: 406-444-6444 | Fax: 406-444-6783
Remediation Web: http://deq.mt.gov/Land/rem

Petroleum Tank Release Compensation Board
1225 Cedar Street | P.O. Box 200901 | Helena, MT 59601
Phone: 406-444-9710 | Fax: 406-444-9711
PTRCB Web: http://deq.mt.gov/DEQAdmin/PET