Total hardness test strips can be used to measure water hardness. The hardness (total hardness) of a given water is due to its content of salts of the alkaline earth metals calcium, magnesium, strontium, and barium (“hardening constituents”, later compounds only in traces).

Total hardness test strips are used to test the hardness of the make up water prior to mixing drilling fluids. Using hardness test indicators can ensure the product being used is suitable for that water type. The effect Total hardness has on make up water can severely alter how a drilling fluid mixes and to what level of yield you will get from that product.