Water hardness is caused almost entirely by calcium and magnesium ions. Other di- and trivalent metals have a similar effect, but usually are not present in high enough concentration in potable waters to cause problems. Hardness increases soap consumption in laundries and causes scale in boilers. With Hach Water Quality Test Strips, technicians in the field can test many samples in only a few minutes, and make immediate evaluations on-site. No measuring, set-up, clean-up, or chemical handling are necessary. Hach test strips are also used in laboratories all over the world for pre-test screening-to detect the presence of materials that might interfere with lab testing. Strips are individually wrapped for maximum portability and stability.