Marney Generators is reader-supported. When you buy through links on our site, we may earn an affiliate commission. Learn more


Zachary Brown
  Feb 3, 2023 9:32 AM

Generators are an essential tool for homeowners. They can be used to power up appliances in the case of an emergency or when the power goes out. If you own a generator, then it is important to have the right accessories to go with it.

One such accessory is a gas tank for your generator. You need fuel to keep your generator running and if you don't have a gas tank, you will have to refuel it manually. This means that you will have to make sure that there is a gas station nearby where you can refuel on demand or buy fuel in large quantities so that they are ready when needed.


The best gas tank for a generator is a necessary component of any portable or backup generator. With a fuel tank, the engine would have the fuel it needs to run. Gas cylinders come in many different sizes and shapes, but they all serve a similar purpose. The size of the tank will determine how long the generator can run before it needs refueling.

The best generator gas tank is the one that meets the needs of the user. Factors to consider include intended use, desired size, and budget.

1. Several types of the best gas tanks for generator

Several different materials may be used to make a gas tank. The most common material is plastic. Lightweight and durable plastic makes it the ideal choice for portable generators. However, plastic gas cylinders can be prone to leaks and must be replaced more often than other cylinders.

Steel is another popular choice for generator gas cylinders. Steel is more expensive than plastic, but it is also more durable. Steel tubs will last longer and leak less than plastic tubs.

Aluminum is the lightest weight option for a gas tank. However, aluminum tubs are more susceptible to corrosion than other materials.

Sub base gas tanks

Sub base gas tanks


If you need to store more than 1,000 gallons of fuel, you'll need an extra tank. As the name suggests, the auxiliary container is designed to be placed on the ground but below the base of the generating set.

The auxiliary base gas tank for the generator has a rectangular cross-section and is a double-walled tank. This helps prevent fuel from spilling out in the event of a leak. Both tanks must be constructed of large gauge welded steel. Several pipes and fittings are attached to the main tank, the important ones being fuel supply and return, air vents, emergency relief valves, and high and low fuel alarms. The tank filling system shall be designed so there is no overflow during filling, and the filling valve automatically closes when the tank is 95% full. After installation, the primary tank is tested at 5 PSIG, and the secondary tank is tested at 3 PSIG.

Underground storage gas tank

Underground storage gas tank


If you need to store more than 1,000 gallons of fuel, you can choose an underground or aboveground storage tank. Installed underground storage tanks are more expensive but have a longer life because they are shielded from the environment. Underground storage gas tanks can be constructed from fiberglass-reinforced plastic. Such tanks are often ribbed to give structural strength. Alternatively, underground storage tanks can be constructed of steel but have sufficient cathodic protection against corrosion from groundwater. Likewise, the underground storage tank pipeline to the generator can be fiberglass-reinforced plastic or steel protected with a cathode.

Leaks and spills in underground storage tanks can be expensive and difficult to fix. Such systems should be equipped with devices and procedures to prevent spills and spills. In the worst-case scenario, installing underground storage tanks should be such that spilled or leaked fuel is contained in a confined area. Therefore, the underground area is surrounded by concrete floors and walls. After the underground storage tanks were installed, the outside area was filled with sand and gravel.

2. What gas should I put in the generator?

When preparing your generator for use, it is essential to perform proper maintenance, especially as a backup power source. You must service many parts on your generator, but we will focus on the two most important: fuel and oil. Here're some of the most important tips to remember when maintaining your generator:


Maintaining your portable generator by regularly servicing the oil in its engine is essential. The last thing you want in an emergency is to turn off your portable generator's engine due to a lack of oil, especially when relying on it for virtual power devices in your home.

You should check the engine oil level every time you use the generator. Usually, every 100 hours, or every season, you should change the oil. However, if you use your generator in harsh conditions, such as in a dusty or dirty environment or extremely hot weather, you should change the oil more often. Also, when disposing of oil, please return it to a collection center to avoid contamination.

OIL portable generator



Before we talk about your fuel maintenance, let's discuss the fuel requirements for your portable generator:

  • Use clean, fresh, unleaded gasoline

  • Fuel must have a minimum octane rating of 87/87 AKI

  • Although up to 10% ethanol is acceptable, ethanol-free premium fuel is recommended

  • DO NOT use E85, gas/oil mixtures, or modify the engine to run on alternative fuels

Depending on the portable generator model, you will need to monitor the fuel gauge, or you will need to check the fuel level manually. You should always turn off the generator when refueling and let it cool down a bit first. This will help cool the hot components and prevent a fire if gasoline is splashed or spilled.


3. How large a tank do I need for the generator?

This depends on the size of your portable generator and how long you plan to run it. For most home uses, we recommend a 120-gallon tank for short-term power outages (1-2 days) or a 500-gallon tank for a longer period (8-10 days).

Below are more accurate estimates based on the size of your portable generator and assuming an average generator load of 50% during downtime.

  • 22kw Generac: 48 hours on a 120-gallon tank / 197 hours on a 500-gallon tank

  • 20kw Generac: 50 hours on a 120-gallon tank / 210 hours on a 500-gallon tank

  • 16kw Generac: 59 hours on a 120-gallon tank / 246 hours on a 500-gallon tank

  • 7.5kw Generac: 138 hours on a 120-gallon tank / 574 hours on a 500-gallon tank


4. Which gas tank capacity is best for you?

In the event of an occasional or short-lived power outage, a smaller tank will cover your fuel needs. However, you will need to buy fuel more often in fewer quantities to refill your tank. Although you incur a low initial investment (capital cost) in tank installation and low maintenance costs, the cost of fuel supply per unit will be higher.

Large storage tanks are required when generators are used to support large commercial facilities or where power outages are frequent and prolonged. In this case, you could buy fuel less often and in larger quantities. However, when setting up your tank, you will incur higher initial costs (capital costs). Maintenance costs will also be high in the long run. On the other hand, fuel cost per delivery unit will decrease as you can order bulk fuel to be delivered in one go. However, you will also need to account for the potential costs arising from the risks of storing a larger amount of fuel.

Before finalizing storage capacity, it is essential to finalize a fuel supply contract with the supplier. The supplier's capacity to supply the required quantity with the required frequency should be assessed, and penalties for breach should be incorporated into the contract.

Which gas tank generator



Gas tanks for generator and associated piping must be approved prior to installation. This is a requirement not only for industrial facilities but also for fuel tanks for domestic or commercial use. Only very small capacity tanks are exempt from approval. You are required to submit a proposal to the State Fire Police. Details provided include production drawings, product data sheets for all additional components purchased, recommended wiring and control diagrams, piping layouts, and instructions for installation.

5 ratings