Composition of Water Supplies Used in Horticulture

The results of a water survey in 1979 based on 77 samples obtained from growers in 18 counties in Ireland indicated that water from wells had the highest total hardness values at 260mg/l (CaCO3) as compared with mains supplies (143 mg/l), river supplies (114mg/l) and samples obtained from glass house roofs (37mg/l). Values for electrical conductivity, calcium and magnesium were in the same order as total harness. Sodium levels were also highest in well samples ( 26mg/l), while the mean zinc levels were less than 0.29,g/l except for samples from glasshouse roofs which had a mean of 0.40mg/l. Due to lack of sufficient samples a valid inter-county comparison could not be made. However, there were large differences in the total harness of water from North and South County Dublin, with values of 198mg/l and 63mg/l (CaCO3) respectively.