The City of Novi Water & Sewer Division data tracking indicates a 14% water loss for the 2011-12 fiscal year. The methods currently in place to track water use in the City of Novi are not based on the same methods we are invoiced by Detroit Water & Sewerage Department. As the Water & Sewer Manager, we are suggesting methods of improving the accuracy of the figures to accurately represent water use on a monthly basis.
Water purchased figures are developed directly from the Detroit Water and Sewerage Department (DWSD) invoices sent to the City of Novi. Using the DWSD Wireless Automated Meter Reading (WAMR) Portal, the volume of water purchased per the invoice is checked for accuracy at the individual meters (five master meters from DWSD). This figure has historically been accurate with the exception of metering errors, which are noted both on the WAMR and the invoice. DWSD invoices the City of Novi on a monthly basis.
Water sold is simply a figure based on the meter reading operation for the Water & Sewer Division. The figure does not take into account any water sold via fire hydrant set-ups or water used in the operations and maintenance of the City of Novi DPS, whether by our designated contractors or City personnel. The accuracy of the water sold figures is compromised by the quarterly reading of water meters. A remedy to enhance the accuracy of tracking water sold would be to read all water meters, including hydrant set-ups, on a monthly basis to cross reference the data with Detroit Water and Sewerage Department (DWSD)’s monthly invoice. Monthly billing of all water meters could remain a standard practice in an effort to reduce the labor costs associated with monthly reading.
Water loss is the most inaccurate figure to track. Many unknown variables effect the estimated quantity recorded in a water loss report. We estimate the quantity of water loss through water main breaks, valve leaks, fire hydrant flow tests, hydrant flushing, and other sources. Accurate hydrant related estimates can be calculated based on the flow and pressure, yet infrastructure leaks have an unknown variable of how long the water has been leaking.
Water loss tracking can be improved by switching to monthly water meter reading. Figures can be analyzed and tracked on a monthly basis as opposed to being surprised at the end of the year. I am currently exploring more efficient water meter reading devices, and should have the remedy in place shortly. Please contact us with questions or comments.