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How to Waterproof a Cistern

Cisterns generally are used for water storage. Cisterns are made with lime plaster materials that are water resistant. Because cisterns have a life span of hundreds of years, the water-resistant materials decompose. To keep the cistern waterproof, use a topical waterproofing solution. When storing water, utilize natural and nontoxic waterproofing materials. Linseed oil is a natural waterproofing material also known as flaxseed oil.

Large cisterns can be used as water tanks.

Step 1

Boil 1 gallon of linseed oil for five minutes in a large pot.  For large areas, boil the linseed oil in a commercial boiler. Boiling linseed oil enhances the waterproofing properties of the oil. 

Step 2

Cool the linseed oil for 20 minutes.  Cool an additional 10 minutes for every gallon of linseed oil used.

Step 3

Pour the linseed oil into an aerosol sprayer.  Pour the linseed oil into a 50-gallon tank commercial sprayer for larger areas. One gallon of linseed oil can cover 100 square feet of surface area. 

Step 4

Spray all surfaces of the cistern with the linseed oil.  Dry the cistern for 20 hours or until completely dry.

Things You Will Need

  • Linseed oil
  • Large pot
  • Commercial boiler
  • Large aerosol sprayer
  • 50-gallon commercial sprayer

Photo Credits

  • Goodshoot/Goodshoot/Getty Images