Blog    |    DIY Plastic Tank Repair 101

DIY Plastic Tank Repair

Good doctors and plumbers always seem impossible to get ahold of when you need them the most. From the outside perspective, they seem to be able to work whenever they want and rake in lots of our own hard-earned money. I am sure that both doctors and plumbers know better. However, it stands to reason that repairs on your plastic tanks could be much less expensive and much more efficient if you were able to do those repairs yourself.

With the following guidelines, you should be able to assess the possibility of repair for your plastic tank. You may be able to infer your own abilities to make the necessary repairs. You will also have a succinct list of equipment and items required to repair your cracked tank, as well as a step-by-step set of detailed instructions that will enable you to perform a plastic weld over the crack in your plastic tank.

What type of tanks can you repair yourself?

Plastic tanks have the benefit of outlasting many other types of tanks and also being much easier to repair. Depending on their function and what they hold, you may need to call a plumber or other expert after all. Plastic tanks can play an essential role in the daily life of your household or business, and it is essential that you know your abilities and limitations before attempting to repair them yourself. When in doubt, seek out a professional plumber or plastic tanks specialist for help.

First of all, it is a misunderstanding held by many people, that you can fix a plastic tank simply by welding the seams of a crack back together again. Welding any crack back together, on virtually any material, creates a weak place that will bear the brunt of any tension the tank receives. It is at best a temporary fix and may end up causing greater harm the next time it ruptures.

Secondly, you need to completely empty your plastic tank before you can attempt to fix it safely. If you are dealing with a small water-collection tank, this is not a challenge. However, large fuel tanks and septic tanks may require you to get professional assistance. In some areas, you may not be legally allowed to fix your plastic tank yourself – especially if it is a large one filled with hazardous materials. Be sure to check your local regulations before digging up a project and getting into legal messes as well as plumbing ones.

That is not encouragement to sit back and do nothing about a crack or leak in your plastic tank, though. Once a crack develops, it will quickly grow to a point where it is no longer repairable. Early intervention is key, whether you are doing the repairs yourself, or calling in a professional plumber or plastic tank expert. It is also important to note the location of the crack. If the crack is near one of the pipes and seals of the tank, you may need to get new fixtures, and you will have to reseal those pipes.

Signs of Plastic Tank Damage

There are no “common” types of cracks, but cracks on the top or sides can be dealt with if you find them in time. For water tanks, the tell-tale signs will be a loss of water pressure, loss of water level in the tank itself without use, or, if housed indoors, you will be able to see the collection of water around and on the outside of the tank. Septic and fuel tank cracks and leaks will often be accompanied by a smell, and sometimes mushy ground around the outside of the tank if it is buried. Anytime you notice an unusual (and usually unpleasant) odor from a fuel or septic tank, you should investigate it immediately.

If your tank forms a crack at the bottom of the tank, this is due to inability to withstand the pressure. Unfortunately, there is no fix for this kind of rupture and your tank will need to be drained and replaced. In these worse-case-scenarios, it is helpful to know that some plastic tank suppliers offer the option of renting tanks while you are in the process of replacing or repairing yours.

Plastic Drinking Water Tanks

One final note before you begin your DIY plastic tank repair: Be careful about trying to fix drinking water tanks yourself. Plastic drinking water tanks need to be made from special plastics that are U/V resistant and do not have the same kind of decay as other plastics. Many types of plastic leach chemicals into their contents over time (which is why plastic water bottles have expiration dates on them). If the plastic patch and plastic tank repair epoxy you use on your drinking water tank do not have the same properties, it may end up leaching chemicals itself, even if the majority of the tank does not. These chemicals are toxic and will end up making your drinking water toxic as well. This would also apply to reservoirs used for indoor gardens.

Plastic Tank Repair Kits

Once you have determined that you can make the repairs yourself, it is time to put together your plastic tank repair kit. In this kit you will need:

  1. Plastic welding gun
  2. Polyethylene welding rod (plastic tank repair epoxy)
  3. Utility knife
  4. Rag
  5. Drill
  6. 1/8th-inch drill bit
  7. Rotary tool
  8. Abrasive rotary tool tip

Making Repairs With Your Plastic Tank Repair Kit

To begin your repairs, you must be sure that both the inside and outside of the tank are clean. This means that any hazardous materials (septic or fuel in particular) need to be professionally removed. Once the inside is empty, you need to clean up the outside area as well as you can with your rag or another cleaning tool. Make sure the area around the crack is free from any dirt or extraneous material.

Next, you need to drill two small holes, one at the top and one at the bottom of the crack. These holes will relieve some of the structural pressure and prevent the crack from growing any larger. Then take your rotary tool from your plastic tank repair kit and sand a groove with your abrasive rotary tool tip ½ inch parallel to the crack, above and beside it. The groove will allow your polyethylene welding rod a place to fit in and seal the crack.

When applying the plastic tank repair epoxy, be certain to follow the directions that accompany it. Many of them are only made to cover small cracks. They also typically have a prescribed temperature for the tank to be at when they are applied. If you are attempting to repair a plastic fuel tank or plastic septic tank, check to ensure that your epoxy is suited for holding such contents.

When you have met all the prescribed requirements of your plastic tank repair epoxy, take your polyethylene welding rod and cut it to a point, like a pencil, with your utility knife. Insert the welding rod into your plastic welding gun. Touch the plastic tank repair epoxy to the top of the crack. Apply pressure per the instructions that came with your plastic welding gun, and pull the gun down or across to the other end of the plastic tank crack. Make sure you allow the plastic tank repair epoxy to dry for at least 1 hour before you move ahead.

Final Touches

The plastic tank repair epoxy will usually dry an off-white color. Once it is completely dry, you may sand it down gently to remove the rough outer edges and paint it over with an appropriate plastic paint that matches the color of the rest of the tank. This may essentially make the damaged area of the tank invisible and perfectly functional again. Be careful to remember that, even if it appears good as new, your tank is no longer structurally the same as when you first bought it, and this may only be a temporary solution.

If the crack you are attempting to repair is over 12 inches long, you should plan to replace the tank very soon. If the crack occurred because of pressure or heat problems (such as if the crack is on the bottom of the tank) you should plan to replace the unit. Any plastic welding you do will be a temporary fix at best, but it will hopefully give you time to save up enough money to have a new tank designed, created, and installed on your property. Don’t forget, you may be able to acquire a rental tank while repairing or waiting for a replacement tank to be made.

With these guidelines, you can accurately assess the possibility of repair for your plastic tank. The information above gives you enough guidance to infer your own abilities to make the necessary repairs. Also, you now have a succinct list of equipment and items required to repair your cracked tank. By following the step-by-step set of detailed instructions, you can perform the plastic weld you need over the crack in your plastic tank.

DIIY Plastic Tank Repair

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