J-PRO-22 Alum Guide Rev 0021622 Page | 13
Solution Strength and Settings for Alum
Alum injection can be used to treat cloudy water. Alum is considered by the FDA as a generally
recognized as safe (GRAS) substance. It is an inorganic salt, also called potassium aluminum sulfate.
A typical system for small well water systems can be set up by injecting the alum prior to the well
pressure tank and allowing the water to flow through to a contact retention tank to allow the alum to
mix and treat the water.
The amount and dosage of Alum varies widely based on water chemistry and we cannot make a firm
recommendation as it must be tried out on site with your particular water.
To start with we recommend injection of alum at 3 to 10 PPM then running through a contact tank as
large as you can get, for example 120 gallons is good.
After alum contact tank filter the water with a sediment backwash filter, with 25/1 micron big blue filter
cartridge and then optionally a Nano-Ceram micro filter to take out very fine particles.
To make up a 2.5% solution (25,000 PPM) mix 1 lbs (which is same as 1-1/4 cups) of alum powder for
every 5 gallons of water, which is approximately a 2.5% solution by weight.
It is best to use warm purified distilled or reverse osmosis water to make up your solution.
You can get some alum and do jar testing as well, which is what water treatment plant operators do.
In municipal water treatment it is OK to inject up to 50 PPM, but it does contain aluminum so it’s
important not to inject more than 50 PPM. 3 to 10 PPM is standard. More alum is not better, generally
you want to inject enough to get the flocculation started in the contact tank. Flocculation is where the
suspended particles clump together to form larger particles that can be filtered.
Each water chemistry is different and alum injection does take some adjustment to achieve the best
results. We recommend starting out with a 5 PPM applied dosage.
After injection, a Sediment / Turbidity Backwash Filter is recommended.
As a final stage, a Nano-Ceram filter system is recommended. This removes fine particles and turbidity
as well as filter coliform bacteria if present.
