Tank Maintenance
Fuel & Diesel Tank Maintenance — Cleaning, Polishing, Removal & Periodic Testing
A storage tank is the heart of your energy system — and quietly its most likely point of failure. Diesel sitting in a tank gradually collects water, sludge, rust and microbial colonies, until the fuel meant to start a backup generator or fire a heating boiler no longer meets standard. Dolek Energy brings the entire tank lifecycle under one roof: thorough cleaning, fuel polishing and filtration, certified removal of residue and sludge, and periodic testing for underground tanks — all delivered nationwide, to standard, with emergency availability.
Years of experience · Nationwide coverage · 24/7 response
[Hero image — large industrial diesel storage tank in an orderly facility at dusk]
Why Tank Maintenance Is Operational Insurance, Not a Luxury
The overwhelming majority of generator failures in an emergency do not come from the generator itself — they come from the fuel feeding it. Diesel is a "living" liquid: it absorbs moisture from the air, and a layer of water forms at the bottom of the tank where bacteria and fungi thrive. Their by-products — sticky sludge and acids — clog filters, damage injection pumps and degrade combustion. In a critical system such as a data center, hospital or factory, the moment this surfaces is the exact moment it must not: when the grid drops and the generator is supposed to take over.
Planned tank maintenance breaks that failure chain before it forms. Instead of discovering the problem at the moment of truth, the tank and the fuel are cleaned, filtered and tested on a scheduled cycle — protecting operational continuity, extending tank life, and keeping you compliant with regulation. That logic guides every maintenance service Dolek Energy provides.
Our Tank Maintenance Services
Tank maintenance is not a single action but a family of services that work together. Dolek Energy provides all of them, so there is no need to coordinate between several vendors — you get one responsible, complete point of contact, from inspection to disposal certificate.
Fuel Tank Cleaning
Thorough cleaning of diesel, fuel, kerosene and heavy-oil tanks: draining and pumping out, removing sludge, rust and sediment from the tank floor and walls, and treating the water layer. Cleaning returns the tank to sound condition, extends its life, and prevents the clogging and corrosion that start silently and end loudly. It is especially relevant for generator tanks that sit for long periods with no fuel movement.
Fuel Polishing & Diesel Filtration
Fuel polishing is a recirculating filtration process that passes the diesel through a multi-stage filter system, separating water and removing particles and microorganisms — returning the fuel to standard without emptying the tank and without discarding the existing diesel. It is the smart solution when the fuel is still usable but has started to degrade, and it complements cleaning as ongoing maintenance.
Diesel Bacteria & Water Treatment
When testing reveals microbial growth, free water or the sludge it produces, the tank needs more than a top-up. We treat the contamination at its source — removing the water layer that feeds the bacteria, filtering out the colonies and by-products, and restoring the diesel to a clean, stable condition. Catching it early is the difference between a routine service and a failed start under load.
Certified Removal of Fuel, Oils & Sludge
Removing old diesel, contaminated fuel, used oils and tank sludge must be handled as hazardous waste, by law. Dolek Energy removes the waste in a controlled manner and provides proper disposal certificates — so you are protected both operationally and from a regulatory standpoint, without getting entangled with hazardous waste or the authorities.
Underground Tank Testing
Underground tanks are out of sight — and that is exactly the risk. An underground leak can contaminate soil and groundwater and expose the owner to heavy liability. Periodic testing checks the tank's integrity and tightness, documents its condition, and ensures compliance with the law. We handle both the test itself and the treatment of any finding.
Storage Tank Supply
Alongside maintenance, we also supply new storage tanks — for diesel, heating oil and fuel — in the volumes and configurations the application requires, including double-wall tanks that match the direction of regulation.
Who Tank Maintenance Is For
Tank maintenance is needed by anyone who owns a fuel or diesel tank — but the level of criticality changes with the use. For data centers and server farms, the tank feeds backup generators that must start without fail, so ongoing polishing and cleaning are essential. Hospitals, institutions and public buildings depend on the same principle of reliable backup power. Factories and industry keep diesel tanks for generators and heating that require maintenance to protect production continuity. Winter venues, residential buildings and hotels need clean heating-oil tanks ahead of the season. Private fueling stations, haulage companies and vehicle fleets rely on stable fuel quality, and agriculture, moshavim and kibbutzim run tanks for generators, pumps and equipment.
The common thread: a neglected tank is a silent risk, and planned maintenance is the cheapest, safest way to prevent it.
How It Works — The Dolek Maintenance Process
We work in a transparent, orderly process, so you know at every stage what is being done and why.
1. Inspection & sampling. We examine the tank and the condition of the fuel, take a sample and diagnose the scope — whether full cleaning, polishing, removal or a combination is needed.
2. Planning & execution. We set a work plan and a coordinated time that minimizes downtime, and carry out cleaning, filtration and removal as required, with dedicated equipment.
3. Fuel & waste handling. We return the in-spec diesel to the system after polishing, and remove waste and sludge in a controlled manner.
4. Reporting & certificates. We provide a work report and disposal certificates, and where relevant recommend the date for the next maintenance.
Standards & Regulatory Compliance
Diesel quality is measured against EN 590 for transport diesel and SI 701 Part 2 for heating oil — and our maintenance is designed to return the fuel to those requirements and keep it there. For underground tanks, periodic tightness testing is required, with a clear regulatory trend toward double-wall tanks. Dolek Energy supports the customer on both fronts — the technical maintenance and legal compliance alike — so tank maintenance is not only equipment care but also legal and environmental protection.
We work to the strictest industry standards: EN 590 · SI 701 Part 2 · IEC 60296 · API CK-4 · DIN 51524-2 · ISO 6743-7
Why Dolek Energy
A full-lifecycle partner
Cleaning, polishing, removal and testing — under one provider. No coordinating between several parties and no gaps in accountability.
Compliance and documentation
We return fuel to standard and provide disposal certificates and documentation on request — industrial trust, not promises.
24/7 availability and emergency response
An emptied tank or a stalled generator does not wait for business hours. Our emergency desk is available around the clock, nationwide.
Frequently Asked Questions
How often should a diesel tank be cleaned?
Frequency depends on usage and storage conditions, but as a rule a generator tank or a diesel tank that stands for long periods should be cleaned every one to three years, with ongoing fuel polishing in between. Tanks in critical systems such as a data center or hospital require higher frequency. After an initial inspection and sampling we can recommend a tailored schedule.
What is the difference between tank cleaning and fuel polishing?
Tank cleaning treats the tank itself — it drains the tank, removes sludge, rust and sediment from the walls and floor, and treats the water layer. Fuel polishing treats the fuel — it passes the diesel through a filter system that separates water and removes particles and bacteria, returning it to standard without emptying the tank. The two are usually combined.
What is diesel bacteria, and why is it dangerous?
Diesel bacteria are microorganisms that grow at the water–fuel interface at the bottom of the tank. They produce sludge and acids that clog filters, corrode the tank and degrade fuel quality, and when a generator starts under load that contamination can stall it. We treat bacteria by removing the water layer that feeds it and filtering out the colonies and their by-products.
Do you provide a disposal certificate?
Yes. Removal of old diesel, contaminated fuel, oils and sludge is handled as hazardous waste by law, and on completion you receive proper disposal certificates — full operational and regulatory protection.
Is underground tank testing mandatory?
Underground tanks are subject to periodic tightness testing, and there is a regulatory trend toward double-wall tanks. Beyond the legal obligation, testing prevents soil and groundwater contamination and the heavy liability that comes with it. We perform the test and handle any finding.
Do you operate nationwide?
Yes. Dolek Energy operates nationwide with a single service desk and a uniform customer experience — from central Israel to the north, Jerusalem and the south, including 24/7 emergency response.
Your tank is your operation's insurance policy — keep it sound.
Cleaning, polishing, removal or periodic testing — Dolek Energy handles the entire tank lifecycle, nationwide and to standard. Get a tailored quote, or talk to us now.