Residential Sub-Meter Information

If you use a lot of water SOLELY for outside purposes - i.e. lawn, garden, pool (water that does not return to our sewerage system for necessary treatment), a sub-meter which measures outside water use only may be cost-effective. The Sewer Usage on your bill would only reflect the "household" or inside portion of the consumption.

You will first need to contact a Registered Master Plumber to determine the on-site plumbing modifications required to provide a separation of household and outside services. Please note: a WSSC Water Registered Master Plumber must install the Sub-Meter.

Minimum costs for installation of a residential sub-meter

One-time WSSC Water Sub-Meter Installation charge:

  • Small Sub-Meter Charge: $261.00
  • Large Sub-Meter Charge: $528.00
  • One-time Inspection Fee: $66.00
  • Plumbing Permit / Inspection Fee: 1st Fixture $132.00  and each additional fixture $53.00

Additional Costs:

  • SDC fees may also apply (Call 301-206-4003 for more information) 
  • On-site plumbing work, arranged with WSSC Water Registered Master Plumber and completed at the property owner's expense*

* WSSC Water cannot estimate this expense. The cost of on-site plumbing is negotiated between the customer/property owner and the Registered Master Plumber who will make the modifications. For further details, contact Permit Services at (301)-206-4003 or toll-free at 1-800-643-8400.

WSSC Water's water consumption and sewer usage charges are based on metered public water use. This is a widely accepted practice when a utility provides both public water and sewer services. Maryland Law requires that WSSC Water shows a separate charge for Water Consumption and for Sewer Usage. The owner, tenant, or occupant who uses water "exclusively" for any purpose which does not enter the sewerage system of the WSSC Water, "shall not be charged a sewer usage charge for the water so used, provided, however, that they pay to the WSSC Water the cost of installing such a separate metered connection."

Using a sub-meter, how is a sample bill calculated?

Main meter registers 45,000 gallons of water (500 gallons per day) in a 90-day billing period. Submeter, measuring outdoor usage, registers 27,000 gallons of water used outside in a 90-day billing period.

Registered difference between the Main Meter and the Submeter consumption is 18,000 gallons of water (200 gallons per day), which represents the amount used in-house and subject to Sewer Usage Charge.

The bill calculations based on this example are:

For water use at average daily consumption (ADC) of 500 gallons: ($4.61 X 45,000)/1,000= $207.45

SEWER USAGE RATE (with a Sub-Meter)
For sewer use at average daily consumption (ADC) of 200 gallons: ($5.08 X 18,000)/1,000 = $91.44

SEWER USAGE RATE (without a Sub-Meter)
For sewer use at average daily consumption (ADC) of 500 gallons: ($6.62 X 45,000)/1,000 = $297.00

Please see our Rates page for more information on our rate structure.

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