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.
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.
Cool the linseed oil for 20 minutes. Cool an additional 10 minutes for every gallon of linseed oil used.
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.
Spray all surfaces of the cistern with the linseed oil. Dry the cistern for 20 hours or until completely dry.