Salts test

A salts test is a method of testing areas affected by moisture and dampness. The test can help identify the type of water by looking for signs of chlorides (usually found in tap water) and nitrates (usually found in groundwater). 

Nitrates are found in water in contact with the ground or soil. They are soluble in water and can be carried in moisture from rising damp. Nitrates indicate that the water has likely been in contact with, or is from, the ground.

The diagnosis of the origin of salts should not be made on the presence of salt alone but considering other information available, such as the moisture distribution within the building. A high nitrate reading may signify that soil water’s evaporation has continued for a long time. Soil salts are hygroscopic.

Chlorides are found in treated tap water. As you know, tap water goes through a treatment process to clean and filter it, with specific chemicals (typically chlorine and fluoride) added to help make the water safe. Often, disinfect the water and prevent it from carrying waterborne diseases. The chloride test looks for these traces. 

The presence of chloride does not necessarily mean moisture comes directly from fresh tap water. It can also be from faulty plumbing connections and pipework.