Demonstration 5
Rainwater Harvesting
Location: Wilmington and Hamilton, MA

Purpose:

• Demonstrate the use of rainwater harvesting systems on a range of properties from small homes to larger institutional or commercial complexes as a means to conserve potable water while sustaining landscaping.
• Reduce use of Ipswich watershed groundwater sources for outdoor watering.
• Quantify the water savings of residents and property managers using rainwater harvesting systems for all or part of their irrigation needs.

Description: Rainwater harvesting systems are designed to capture runoff from rooftops and store the water for nonpotable uses, such as lawn and garden watering. The systems are intended to reduce demand on public water supplies by replacing potable water with rainwater, where appropriate.

This project fundeed installation of 39 rainwater harvesting systems on residential properties in Wilmington. The systems consist of a storage tank, a pressure pump to aid in water distribution, a spigot for a hose, and a water meter to measure flow. Two different sizes of storage tanks were installed:  twenty-eight 200-gallon and eleven 800-gallon tanks.

Additionally, a large-capacity (8,000-gallon) underground storage vault was installed at the Boutwell Elementary School in Wilmington, to supply water for irrigating the adjacent ball field, and a 200-gallon system was installed at the Winthrop Elementary School in Hamilton as part of an “Outdoor Classroom” educational program.

Reducing lawn watering, if done throughout the entire Ipswich River watershed, could have a significant impact on river flows. According to the analyses completed for the Ipswich River Watershed Action Plan, lawn watering accounts for 15 to 20 million gallons per day of water use in the watershed – about the same amount scientists have estimated is needed to restore flows in the Ipswich River to normal, healthy levels. Because roof runoff not taken up by plants can be a source of replenishment to groundwater, rainwater harvesting techniques are most beneficial when combined with drought-resistant landscaping techniques to reduce overall irrigation needs of the plants.

Data Collection and Analysis: The water meters attached to each rainwater harvesting system provide data on the volume of rainwater pumped from the storage tanks for outdoor use. In addition, the Wilmington Water Department records on each residential participant’s domestic water use were analyzed to compare domestic water demand before and after installation of the rainwater harvesting system.

Partners:

• Town of Wilmington
• The Winthrop Elementary School in Hamilton
• Rainwater Recovery, Inc., Waltham, MA

Status: See Progress Report