The scope of this standard is the sludges, i.e. all sludges products from: storm water handling; night soil; urban waste water collecting systems; urban waste water treatment plants; treating industrial waste water similar to urban waste water; water supply treatment plants; water distribution systems; but excluding hazardous sludges from industry. This method is applicable to the determination of pH values of sludges which include liquid, paste-like or solid matter. If the sludge sample is sufficiently liquid, direct measurement should be made. If the sludge sample contains relatively high percentages of the solids the measurement should be carried out aft