TRISODIUM PHOSPHATE... just uttering the name sends chills down the spine, doesn't it?  For those of you who don't know, trisodium phosphate was a synonym for pure cleaning power!! For many years, compounds similar to this were used in clothes and dishwashing detergents... until the damage that phosphates caused to the environment was realized. Now the power of phosphates is limited, but you can still purchase and use it in its purest form, TSP.

What damage to the environment, you say? Well, the story goes that the release of vast quantities of phosphates into the open environment caused a shift in the balance of life in lakes, rivers, and streams. Phosphate-loving algae flourished, removing much of the oxygen from the water due to their rapid reproduction, leaving other plant and animal life at risk. In the early '70's, limitations on the use of phosphates were implemented in the US and Canada.

Uses for TSP...

TSP is used for washing surfaces prior to painting, especially exterior surfaces. Liquid bleach is often added to TSP if there is mildew on the surfaces. The TSP and bleach act in concert to both kill the mildew and remove its characteristic stains. It may be used on inside surfaces also, but try to mask all surfaces except the one you want to clean. It can damage many metal and painted surfaces, and can stain woods. It is not recommended for use on glass, either, since it will leave a filmy residue.

TSP can also be used as a masonry cleaner. However, if efflorescence or mortar staining are severe, you may need to resort to a more powerful but dangerous product, muriatic acid.

TSP and TSP-bleach solutions may be applied with a sponge or brush, or can be sprayed on. Generally, you will have to apply some elbow-grease if the mildew or other staining is severe. If you are washing the exterior of a house, it may be worthwhile for you to look into the rental of commercial powerwashing equipment. You may be able to do all necessary cleaning from the ground level, sparing you the risk of extra ladderwork.

Mixing TSP...

TSP is a very strong cleaner at the dilutions normally used, which vary from 1/2 cup TSP to 2 gal. warm water for "heavy duty cleaning"  to 1 cup TSP to 3 quarts warm water for "ridiculously heavy duty cleaning"  (source The Savogran Company).  For mildew killing, household bleach is added to the TSP/water mixture.  The recommended ratio is 1 part household bleach to 4 parts water.

Read the manufacturer's mixing ratios, as they may vary.


TSP is a strong base and can cause severe eye damage and can burn unprotected skin.

Wear suitable clothing and eye protection. Keep away from skin and out of gloves.

Any foliage near where TSP is to be used should be soaked with plain water prior to the application of TSP, and rinsed down afterward. Be sure to read and follow all warnings on the product's packaging.

TSP is not recommended for cleaning in bathrooms...

TSP can cause staining to metals such as shower doors, chromed drains and plumbing fixtures, and can also etch the glazing on ceramic tile if left in contact too long.  It can also attack the grout... it is an ingredient in products used to remove dried grout from tile surfaces in new installations.

If you think the TSP is going to perform a miracle on your tile grout that you can't accomplish with regular cleansers, bleaches, and scum removers, you will be disappointed and possibly make the situation worse.  I have seen hundreds of stained tile enclosures, tubs, fiberglass stalls, and shower pans.  Once stains are set, they are often unyielding.