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GreenStep City Best Practices Environmental Management

Efficient Water and Wastewater Systems
no. 20

Assess and improve city drinking water and wastewater systems and related facilities.
  • Minnesota's 1000 wastewater and drinking water plants use 1 billion kWh of energy per year, costing $80 million. Energy efficiency upgrades of 10% at all of them would result in 100 million kWh and $7 million saved.
  • Twin Cities metropolitan cities have spent, since 2005, about $136 million to reduce inflow and infiltration (I & I). These investments are ensuring that the region can avoid the unnecessary expense, estimated at $1 billion, to build excess capacity in the regional wastewater collection and treatment capacity to handle excess I/I.
  • The risk management benefits of adapting water utilities to a changing climate are becoming clear: see resources under best practice action 29.5
  • When cities work with their businesses to implement pollution prevention programs to minimize water use and contaminant loading, including phosphorus, publicly owned treatment works can benefit by:
    • Maximizing existing sewer and treatment capacity to avoid further investments in water supply and treatment infrastructure.
    • Reducing chemical, energy, and sludge management costs.
    • Improving biosolids quality through reduced loading of heavy metals.
    • Help meeting the increasingly strict National Pollutant Discharge Elimination System (NPDES) permit limits by reducing wastewater loading from industrial users.
    • Strengthening local industry by helping businesses reduce wastes, cut costs and meet regulatory requirements.
    • Minimizing risk of damage to pipes and sewage treatment equipment from industrial solvents and corrosives, thus reducing costs.
    • Lessening workplace exposure of toxic chemicals to employees at publicly owned treatment works (POTWs).
    • Protecting drinking water sources in the community by minimizing discharge of contaminants, especially in wellhead protection areas.
Optional for category A, B and C cities
All Category C cities that provide drinking water services and choose to implement this best practice are recognized upon completion of at least actions 1 and 2, or action 4.

Category A and B cities that choose to implement this best practice are recognized upon completion of actions 1 and 2 and at least one additional action.
Conserving water in and reducing wastewater flows from homes and businesses effectively adds capacity to city infrastructure. Cities can promote such actions, which are found in several best practices, including Existing Buildings and Green Business Development. Actions in this best practice include using pricing signals and making water and wastewater infrastructure more energy and materials efficient so as to achieve significant environmental and economic benefits to a city. Benefits include reducing carbon emissions from water and wastewater systems, which can easily make up one quarter or more of the city operations' carbon footprint.
greenstep advisor
Karl DeWahl, Senior Engineer, Minnesota Technical Assistance Program: 612/624-4645, dewah001@umn.edu, http://mntap.umn.edu/us/staff.htm
connection to state Policy

  • Allowing inflow - clear water that enters a wastewater system through rain leaders, sump pumps or foundation drains that are connected to the sewer lines - has been illegal in Minnesota since 1968.
  • Every public water utility serving more than 1,000 people must adopt a conservation rate structure or a uniform rate structure combined with demand reduction methods by January 2015.
  • Every water utility must create a capacity use plan and verify that there is enough water to meet projected needs out 25 years in the metro area and out 10 years beyond the metro. In the metro area such planning is urgent because more than half the water supplied by municipal utilities comes from only one aquifer, which is being mined, with groundwater levels going down across the metro region.
  • New state plumbing code rules taking effect in January 2016 provide for reuse of treated rainwater within buildings for toilet flushing, vehicle washing, industrial processes, water features, cooling tower makeup and similar uses.