The demand for natural resources increases as population and industrial development increases. While water conservation is not a new concept, the limited supply of fresh drinking water is becoming an increasing concern, particularly for dry areas and areas surrounded by sea water. By collecting rainwater for various uses, including drinking water, these places (and any place) can significantly reduce their dependency on water storage dams. Reduced dependency leads to fewer dam expansions and creations, less burden on stormwater systems, and, not to be undervalued, reduced water bills.

Rainwater collection can be used as a part of a sustainable water management practice. When rainwater is used for drinking, cooking, or showering, it is important to know that the material of the collection system is an added health concern. To address this concern, NSF International developed NSF Protocol P151, Health Effects from Rainwater Catchment System Components. This testing protocol covers gutters, barrier materials and/or catchment surfaces such as coatings, paints, lining and liners placed on roof tops and ground surfaces that come in direct contact with rainwater that is collected and used as drinking water. This NSF Protocol was developed to assess the safety concern of materials that are coming into contact with rainwater intended for drinking.

In evaluating a rainwater catchment system component, NSF considers the support of microbiological growth; reviews literature and labeling for clarity of end use, installation instructions, maintenance, etc.; and the safety of materials used in the product.

To simulate field conditions over the lifetime of the product, the product’s safety is tested before and after accelerated weathering procedures. It will be evaluated to determine whether the materials support unacceptable microbiological growth and if concentration of a contaminant extracted from surfaces and components exposed to rain exceeds known drinking water maximum contaminants and/or health advisories under test conditions that simulate the life of the product.

It is important to note that the protocol addresses the safety of the materials only. As such, the quality of the collected rainwater and its acceptability for use as drinking water is the responsibility of the appropriate regulatory agency with authority.

The current listed  products to NSF Protocol P151, Health Effects from Rainwater Catchment System Components, can be viewed at As concerns about limited supply of fresh water grows, it is expected that the number of certified companies offering safe rainwater catchment system components will grow to meet the demands of those who want to seek the sustainable water management practice of using rainwater for household applications, including drinking water.