When applied according to Guidelines and good farming practices, Biosolids will not impact on groundwater or surface water quality.
As with any fertiliser, the chief groundwater issues are nitrogen and phosphorous. Unlike many commercial fertilisers, about 85% of the nitrogen in biosolids is present in a slow-release organic form, making biosolids less likely to cause groundwater pollution from the release of nitrates (the mobile form of nitrogen) or phosphates. In addition, many Guidelines ensure soil pH is taken into account and is managed in establishing the suitability of a site for land application to prevent movement of metals through the soil.
Guidelines for land application of Biosolids usually specify site selection criteria, stormwater controls at the site as well as operating practices to minimise stormwater runoff under extreme events. Please refer to State, Territory and national Guidelines for further detailed information. Links to most of these can be found here.