Contact 202-612-3500 to schedule a service order to install a meter on cooling towers or irrigation systems. The service must be “meter ready,” meaning that the service must already have meter connections present. Services must not be installed above 4 feet from the ground or less than 17 inches from the ground and safely accessible for our technicians. Failure to meet these requirements may result in loss of credits for your sewer charges.

Backflow Prevention Assembly Fee (BPAF) – Beginning August 2019, customers will be billed for each backflow prevention assembly (BPA) on their property. BPAs are required by law to prevent non-potable water from mixing with potable water. Points where this can occur are called “cross-connections” and include lawn irrigation, fire sprinklers, swimming pools, boilers, cooling towers, chillers, and other systems.

Revenue Subtractions:

Cooling Towers Credit – These are credits given to buildings where water is delivered for HVAC/air conditioning purposes in which the water generally circulates through a series of cooling pipes throughout a building and any wastewater from the cooling process evaporates rather than being discharged into the sewer system. The water used in the HVAC system is exempt from sewer fees and is only charged the remaining volumetric fees (water, right of way and pilot). The volumes can be calculated two ways: through direct measurement of water metered through a cooling tower meter, or through a credit calculation based on the tonnage (capacity) of the cooling equipment, multiplied by a seasonal use factor, then multiplied by the number of days in the billing period. This is generally a large commercial/government building setup, although some large condominium associations with master meters have also used these systems.

Irrigation Credit/Exemption – This credit is given to property owners with separately metered ground irrigation systems in which water delivered for this purpose is used for landscaping and does not go into the sewer system. This water consumption is charged all of the volumetric rates except for sewer. The consumption going to irrigation use is separately metered from the domestic use. There are two ways this can be billed, depending on how the service line to the house is constructed. If there are two separate service lines (one for domestic use and a separate line for the irrigation use), then the domestic line is billed normally with all charges, and the irrigation line is exempted from sewer charges and billed all other fixed/volumetric charges. If there is only one main service line to the house, and the irrigation meter is downstream, or sub-metered, to the main domestic use meter, then the second meter is used to calculate a subtraction credit, in which a percentage of the water usage recorded at the first meter is subtracted and the resulting value is used to calculate a sewer credit.

• Irrigation credits and cooling towers credits.
• All irrigation credits are metered

FY	Credits	Metered Accounts	Non-Metered Accounts
2011*	$5.9 mil	197	592

* As of April 18, 2011

SECTION 705 - METERING

705.1 Metering

Water consumed from any source associated with the building or building site shall be metered. Each potable and reclaimed source of water, and each onsite nonpotable water source, shall be metered separately. Meters shall be installed in accordance with the requirements of the Plumbing Code. For the purposes of Section 705.1.1, each meter identified in Table 705.1.1 shall be capable of communicating water consumption data remotely and at a minimum, be capable of providing daily data with electronic data storage and reporting capability that can produce reports that show daily, monthly, and annual water consumption.

705.1.1 Metering

All potable and nonpotable water supplied to the applications listed in Table 705.1.1 shall be individually metered in accordance with the requirements indicated in Table 705.1.1. Similar appliances and equipment shall be permitted to be grouped and supplied from piping connected to a single meter.

TABLE 705.1.1 - METERING REQUIREMENTS

APPLICATION	REQUIREMENTS
Irrigation	Irrigation systems that are automatically controlled shall be metered.
Tenant spaces	Tenant spaces that are estimated to consume over 1000 gallons of water per day shall be metered individually.
Onsite water collection systems	The makeup water lines supplying onsite water collection systems shall be metered.
Ornamental water features	Ornamental water features with a permanently installed water supply shall be required to utilize a meter on makeup water supply lines.
Pools and in-ground spas	Indoor and outdoor pools and in-ground spas shall be required to utilize a meter on makeup water supply lines.
Cooling towers	Cooling towers of 100 tons capacity or greater or groups of towers shall be required to utilize a meter on makeup water and blow-down water supply lines.
Steam boilers	The makeup water supply line to steam boilers anticipated to draw more than 100,000 gallons annually or having a rating of 500,000 Btu/h or greater shall be metered.
Industrial processes	Industrial processes consuming more than 1,000 gallons per day on average shall be metered individually.
Evaporative coolers	Evaporative coolers supplying in excess of 0.6 gpm, on average, makeup water shall be metered.
Fluid coolers and chillers	Water-cooled fluid coolers and chillers that do not utilize closed-loop recirculation shall be metered.
Roof spray systems	Roof spray systems for irrigating vegetated roofs or thermal conditioning shall be metered.

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For SI: 1 gallon = 3.8 L, 1 gallon per minute = 3.8 Lpm, 1 ton = 12,000 Btu, 1 British thermal unit per hour = 0.00029 kWh.

7 Rainwater Harvesting

7.1 Description

The practice of rainwater harvesting includes the storage of stormwater for later reuse on the site. The types of suitable uses can include such non-potable demands as landscape irrigation, use in toilets and urinals, use in cooling towers, exterior washing applications, supply for replenishing water fountains or other features, or sprinkler systems. Use of stormwater for these purposes can reduce the volume of runoff from the site and reduces the demand from potable sources.

While the specific design and type of rainwater harvesting systems can vary significantly, there are basic components that most have in common (more specifics are provided in Section 7.3:

• Rooftop • Collection/conveyance system • Screen and first-flush diverter • Cistern/storage system • Distribution system • Overflow system

Rainwater can be stored in tanks or cisterns made of fiberglass, concrete, plastic, brick, or other materials. They can be located above or below ground and can be sized to contain various volumes to meet the desired goals of the project.

The practice of harvesting rainwater is ideally suited for urban situations – while space is limited, this practice can be designed to fit in the urban landscape and many of the re-use applications are suitable for high density, urban environments where higher water demands exist. An important consideration, however, is that certain re-uses require and are subject to review and approval from the local regulatory authority.

3.3 Rainwater Harvesting

Definition. Rainwater harvesting systems store rainfall and release it for future use. Rainwater that falls on a rooftop or other impervious surface is collected and conveyed into an above- or below-ground tank (also referred to as a cistern), where it is stored for non-potable uses or for on-site disposal or infiltration as stormwater. Cisterns can be sized for commercial as well as residential purposes. Residential cisterns are commonly called rain barrels. The design includes the following:

R-1 Rainwater harvesting for non-potable uses

Non-potable uses of harvested rainwater may include the following:

• Landscape irrigation,
• Exterior washing (e.g., car washes, building facades, sidewalks, street sweepers, and fire trucks),
• Flushing of toilets and urinals,
• Fire suppression (e.g., sprinkler systems),
• Supply for cooling towers, evaporative coolers, fluid coolers, and chillers,
• Supplemental water for closed loop systems and steam boilers,
• Replenishment of water features and water fountains,
• Distribution to a green wall or living wall system, and
• Laundry.

By providing a reliable and renewable source of water to end users, rainwater harvesting systems can also have environmental and economic benefits beyond stormwater management (e.g., increased water conservation, water supply during drought and mandatory municipal water supply restrictions, decreased demand on municipal water supply, decreased water costs for the end user, and potential for increased groundwater recharge).

Based on these concepts, this specification focuses on system design configurations that harvest rainwater for internal building uses, seasonal irrigation, and other activities, such as cooling tower use and vehicle washing. While harvested rainwater will be in year-round demand for many internal building uses, some other uses will have varied demand depending on the time of year (e.g., cooling towers and seasonal irrigation). Thus, a lower retention value is assigned to a type of use that has reduced demand.