We evaluate the management of filter media according to the filter media for water supply (JWWA A 103-1988) established by the Japan Water Works Association.
The table below summarizes the test methods for each item　and the meanings of those items.

item	Description
appearance	Visually check the appearance (shape) of the filter media　and whether impurities are mixed. There are different standards depending on the filter material. In the case of filtered sand, there are few impurities, flat　or fragile sand,　and iron sand,　and in the case of anthracite, there are few fine powder, flat,　and scaly ones. It is determined that the content of impurities such as crushed stone　and peat is low.
Effective diameter	The 10% passage diameter of the particle size addition curve is expressed in mm,　and is widely used as a representative diameter of filter media.
Equal coefficient	The ratio of the 60% pass diameter to the 10% pass diameter of the particle size addition curve is an index showing the uniformity of the filter media particle size.
Cleaning turbidity	The dirt that peels off by mixing the filter material　and purified water　and shaking vigorously is quantified as turbidity. It is an index of the cleanliness (dirt limit) of the filter material.
Ignition weight loss	It is calculated from the mass lost when the filter material is heated at 925 ± 25 ° C for 30 minutes. It is an index of the degree of contamination of organic impurities contained in the filter medium　and impurities such as coal grains, limestone　and shells.
density	Indicates the mass per unit volume of the filter medium. In the case of anthracite　and filtered sand, ores such as limestone　and heavy metals may be mixed in if the density changes. The density without voids in the filter media is called the density　or true density,　and the density with voids in the filter media is called the apparent density.
Abrasion rate	Put 5 6.5mm steel balls　and 50g of filter media in a brass　or stainless steel cylinder that can be sealed, shake vigorously up　and down,　and calculate from the ratio of crushing (0.300mm　or less). This is an index of the resistance to crushing　and wear due to backwashing.
Hydrochloric acid solubility	The filter medium is immersed in hydrochloric acid (1 + 1) at 36 ± 1 ° C for 1 hour,　and is calculated from the rate of dissolution　and loss. It is an index of the content of substances (metals such as limestone, shells　and iron) that are dissolved by hydrochloric acid.