Marinetalk is supported by its audience. When you purchase through links on our site, we may earn an affiliate commission. Learn more

How To Drain Gas from Boat Fuel Tank Easily and Safely?

Fact checked by William Hart

how to drain gas from boat fuel tanks

One common task every boat owner must carry out is to remove gas from the boat fuel tank. It might be for gas tank cleaning or gas changing in case of fuel contamination. Also, some owners drain the boat gas tank in the winter when the boat is not in use. The good news is you won’t need professional help, as draining a boat fuel tank is relatively simple and straightforward.

You will need to choose the fuel transfer pump type that suits you: a manual, electric, battery, or DIY one. The procedure varies depending on the pump type. But in short, you will need to jam one end of the pump in the gas tank. Then, put the other end in a container, make sure the container is placed lower than the tank. After that, start pumping and wait until all fuel is removed. Finally, wash the pump and store it.

For further details on each step of how to drain gas from boat fuel tank. Dive in!

Table of Contents

What You Will Need


Gather the following to carry out the procedure.

A fuel transfer pump


Fuel transfer pumps are used to move fuel from the tank to another place. There are many types of fuel pumps in the market. The price varies too. Choose one that suits your needs.

  • Manual: You can find manual transfer pumps at marina stores for around $10 to $20. This pump type is cost-effective. However, you need to pump the device to drain a boat fuel tank physically. For individuals who only do fuel transferring once in a blue moon, this is a nice option.
  • Electric or battery: These types of pumps function with the power of electricity or battery. They can cost up to a few hundred dollars. If you are working with a large gas tank, consider these. Plus, they are a nice long-term investment for boat repairing in the future. Some top brands are Fill-Rite and Tera Pump.
  • DIY: For all the DIYers, we have great news, you can make your own fuel transfer pump. You will need a hose. This fuel hose is to be jammed in the tank to siphon gas out of a boat, so the size should be around ⅜ inch. Also, make sure it is long enough to access the bottom of the tank.

Don’t even think about using your mouth to siphon the fuel. It is dangerous to inhale the gas, let alone swallowing it by accident. With that said, besides the hose, you will need a primer bulb, two hose clamps that fit the hose’s size, and a screwdriver. This technique is a bit old-fashioned; only carrying it out if you have the tools available. Otherwise, we recommend buying a manual transfer pump. The cost is relatively the same, but it will save you time and energy.

Later in the article, we will provide techniques that you can use to drain gas tank with all the types of pumps above. Keep reading.

A container


Prepare a container that is large enough to hold all fuel from the tank.

Safety gear

Working closely with gas can cause allergies like red rashes, itches, bumps, or blisters. Always wear safety gear like goggles, rubber gloves, or safety clothing. We also recommend a mask to avoid gas inhaling. Depending on your conditions, prepare the safety gear as needed.

Steps to Drain the Gas Tank


Step 1: Before proceeding, prepare the workspace by

  • Moving your boat out of the water to a dry, ventilated place.
  • Making sure there is no open flame or ignition source in your working space. A light flame on a cigarette can cause an explosion when meeting with gas.
  • Having a fire extinguisher handy in case of emergency.

Drain fuel tank using the corresponding techniques with the type of pump you choose.

Manual siphon pumps

  • Before using, make sure there is no liquid left in the pump.
  • The end of the hose must be lower than the pump. In other words, your container must be placed lower than the gas tank.
  • Submerge the suction pump in the gas. Ensure it reaches the bottom of the tank.
  • Constantly move the pump up and down until the flow starts. The pump must remain in the gas during siphoning. Keep going until the tank is drained. It might take 5 to 10 minutes, depending on the tank size.
  • Clean the siphon pump thoroughly, let it dry, and store it in a cool, dry place. Never store it without cleaning, as residues from the gas can ignite a flame.

Step 2: Electric and battery fuel transfer pumps

Some electric and battery pumps require slightly different procedures. Therefore, please follow the instructions in the user’s manual if there is. Otherwise, proceed as the following steps:

  • Check if the pump is clean, with no liquid or residues left from the previous use.
  • The container must be placed lower than the gas tank.
  • Prevent air from getting into the hose by submerging the suction pump entirely in the gas before switching the device on.
  • Jam the other end of the hose into the container and turn on the switch. Never let the electric pump be upside down when it’s working. It should take from 5 to 10 minutes for the tank to be drained.
  • Thoroughly clean the pump, let it dry, and store it in a dry, cool place.

Step 3: DIY fuel transfer pumps

To make a fuel transfer pump, firstly, chop your ⅜ inch hose into two pieces. Then, connect one hose to the primer bulb using the hose clamp as a connector. In most cases, that’s it. However, use the help of the screwdriver if you need to.

Do the same thing for the other end of the primer bulb and the other hose line. There you have a hand-made fuel transfer pump. Steps to siphon gas from a boat using this DIY pump is similar to that of a manual one:

  • Before using, the hose must be free from all kinds of liquid and residues.
  • Place the container lower than the boat gas tank so the gas can be transferred.
  • Put one end of the pump in gas. Make sure you put the right end in. The arrows on the primer bulb must point away from the tank.
  • Put the other end into the container you’ve prepared. Then, pump the primer bulb to start the flow. Wait until all fuel is out of the tank. For a large gas tank, siphoning gas from a boat using a DIY or manual pump can take up to 10 minutes.
  • Wash the hoses thoroughly, let it dry, and store it in a dry, cool place.

Step 4: Whatever procedure you choose to follow, always ensure safety by

  • Wearing safety gear as needed.
  • Be careful not to spill gas on the ground.
  • If you intend to dispose of the gas, please put it in the proper container and only dispose of it at an approved local disposal site.


Once you get used to it, siphoning gas from a boat is relatively simple and easy. Still, that doesn’t mean safety while proceeding can be taken lightly. Please follow our guidelines cautiously and carefully whenever you carry out the procedure.

Feel free to save the article on how to drain gas from boat fuel tank for further use, and let us know your thoughts in the comment section. See you next time!

5/5 - (6 votes)