Michigan's Department of Environment, Great Lakes, and Energy (EGLE) regularly receives questions, and sometimes complaints, related to regulation of residential wastewater discharges.

Pool water

Homeowners frequently contact EGLE wanting to discharge pool water to the ground, a storm sewer, or other surface water body. For this guidance, “pool water” is defined as “residential chlorine or bromine-treated swimming pool or hot tub wastewater.” “Pool water” does not include non-residential pools, splash pads, or hot tubs or any types of saltwater pools, splash pads, or hot tubs. If possible, all pool water discharges should be directed to the ground. Discharges of pool water meet the groundwater discharge permit exemption for domestic wastewater (meaning that a groundwater discharge permit is not needed) if the conditions listed below (to remove pollutants and avoid nuisance conditions) are followed:

• The pool water is discharged to the ground surface, not into a septic system.
• The pool or hot tub is left uncovered and exposed to sunlight for about two weeks to remove the chlorine or bromine in the water or until testing shows that no chlorine or bromine remains in the water.
• All discharged water remains on the pool/hot tub-owners’ property and the discharge does not cause physical damage or nuisance conditions (such as flooding) on neighboring properties.

If a discharge to the ground is not possible and a discharge to a storm sewer or directly to surface waters is the only option, the following conditions must be followed by the homeowner with pool water. These conditions typically satisfy requirements of a wastewater discharge permit, although the homeowner does not have to apply for, and obtain, one:

• Leave the pool or hot tub uncovered and exposed to sunlight for two weeks to remove the chlorine or bromine in the water or until testing shows that no chlorine or bromine remains in the water.
• The swimming pool or hot tub filter backwash wastewater cannot be discharged to a surface water or storm sewer.
• No solids should be discharged with the water (e.g. leaves, dirt).
• Hot tub water should be cooled before discharge.
• If a discharge is planned directly to surface waters, it should be done slowly and in a manner that prevents erosion.

Please note that saltwater pools/hot tubs and non-residential pools/hot tubs cannot be discharged to storm sewers or surface waters without applying for, and obtaining, a NPDES permit. If the discharge of a saltwater pool or hot tub is to the ground, steps may need to be taken to reduce the sodium and chloride content prior to discharge; contact EGLE groundwater permit compliance district staff to discuss groundwater permits and possible permit exemptions.

Other home wastewater discharges

 Homeowners also frequently ask about the discharge of non-sanitary sewage wastewater that is generated as part of the normal occupation of a residence. All sanitary sewage, which includes but is not limited to, wastewater from toilets, sinks, showers, washing machines and dishwashers, must be directed to municipal sanitary sewer or to an onsite septic system. In most cases, discharges of non-sanitary sewage wastewater, which is generated as part of the normal occupation of a residence, should be directed to the municipal sanitary sewer (not a storm water sewer), if available. If municipal sanitary sewer is not available, discharge to the ground (not to an onsite septic system) is generally recommended and can be done without a groundwater discharge permit. The discharged water must soak in on the property where it was generated and the discharge must be managed to not create any nuisance conditions. The person doing the discharge is responsible for ensuring that any water they discharge is not going to hurt the groundwater it is discharged to and that the discharge is not going to create a site of environmental contamination. Examples of wastewater that can be discharged to the ground without a groundwater discharge permit include:

• Wastewater from a portable power washer when used by the occupant of a household for washing buildings, vehicles, or other surfaces associated with the domestic occupation of the household. More information on this topic is available in EGLE’s Mobile Power Washing Environmental Compliance Guidance.
• Backwash water coming from a residential drinking water treatment filter.
• Carpet cleaning wastewater discharged by a noncommercial operator or by a commercial operator at a site receiving wastewater from not more than one location where carpet cleaning has occurred. More information on this topic is available in EGLE’s Carpet Cleaning Wastewater Guidance. 
• Any other potable (i.e. drinking) water used for domestic activities other than sanitary sewage disposal (such as irrigation water).

Steps should be taken to prevent the wastewater resulting from the activities listed above from entering any nearby surface water bodies.  

Heat Pumps

Wastewater from residential heat pumps with a heat exchange capacity of 300,000 Btu per hour or less and where no chemical is added to the system can be discharged to the ground without a groundwater discharge permit. The discharged water should remain on the heat pump owners’ property and the discharge cannot cause physical damage or nuisance conditions (such as flooding) on neighboring properties.

In limited cases where the discharge of residential heat pump water would not remain on the heat pump owners’ property and could cause physical damage or nuisance conditions (such as flooding) on neighboring properties, this water may be directed to surface waters or storm sewers. An NPDES permit would not be required for this discharge.

Homeowners with heat pump systems that have a heat exchange capacity above 300,000 Btu per hour, or where a chemical is added to the system should reach out to EGLE staff to determine permitting requirements. For discharges to groundwater, contact EGLE groundwater permit compliance district staff; and for discharges to surface water, contact EGLE NPDES permit compliance district staff.

More information on regulatory requirements for geothermal heat pumps is available on the EGLE’s Geothermal Heat Pumps webpage.

These discharges are regulated pursuant to Part 31, Water Resources Protection, of the Natural Resources and Environmental Protection Act (NREPA), Public Act 451 of 1994, as amended and the Part 22 Groundwater Quality Rules. The law and rules provide that a person does not need a permit for the discharge of the types of residential wastewater as described above, but also does not waive liability for causing injury to the waters of the state. This means the discharge cannot cause waters of the state to lose their usefulness for drinking, agriculture, recreation, industry, or other “protected” uses. To not need a permit, some general conditions apply to these discharges, chiefly:

• A prohibition against causing physical damage to neighboring properties or creating nuisance conditions (i.e., flooding and over spraying).
• A prohibition against creating a site of environmental contamination that would need to be cleaned up.
• A prohibition against certain discharges in close proximity to available sanitary sewer systems. Basically, homeowners should consider sending domestic wastewater to the sanitary sewer if they are hooked up.