Water main Cleaning Program

Water mains are underground pipes that carry water from the pumping stations to your street and the service pipes connected to your house.

The goal of the Water main Cleaning Program is to minimize the occurrence of discoloured water and ensure customers receive the freshest water possible by removing accumulated material from the water mains.

Discoloured water results when iron and manganense, minerals that are naturally present in Guelph’s groundwater, combine with chlorine to form small rust particles or flakes. These particles normally settle on the bottom of the water main piping. However, these particles can mix with flowing water to cause discoloured water during system maintenance, when water is drawn from hydrants for fire-fighting, and during times of high water use.

The Water main Cleaning Program consists of a combination of water main swabbing and flushing to remove accumulated sediments from the water main piping.

Frequently asked questions

What is water main swabbing and flushing?

Water main swabbing entails inserting a soft material shaped like a bullet into the water main through a fire hydrant. The diameter is slightly larger than the water main and the bullet (swab) is pushed along the water main by water pressure. As it passes through the water main, the swab executes a scouring action on the sediment inside the water main.

During water main flushing, high velocity water flowing from hydrants is used to remove loose sediment from water mains.

When does the City clean water mains?

Water main cleaning is usually done in the spring and fall of the year. Cleaning priorities are driven both by water quality and discoloured water complaints.

How does the City notify customers affected by the program?

We use a number of methods to inform customers of planned water main cleaning and possible discoloured water caused by the program. Notification is done by the following methods:

  • Hand-delivery of notices to each customer’s mailbox
  • Advertisements on the local radio stations CJOY 1460 and Magic FM 106.1
  • Advertisements in the City News section of the Guelph Mercury Tribune newspaper
  • Information posted on the City web site at guelph.ca/water
  • Information shared through the City’s official social media accounts (Twitter and Facebook)

What should I do when the water main on my street is being cleaned?

Before the water main cleaning on your street begins, you should:

  • Fill a clean container with tap water for drinking and cooking and store this container in your fridge;
  • Complete dishwashing, clothes washing, and other water use activities prior to the water main cleaning start time indicated on the notice you received;
  • Fill your bathtub with water for use around the house;
  • Use a pail to transfer water from the bathtub to your toilet bowl to allow your toilet to flush; and
  • Turn water softener on bypass or shut off main water supply using internal stop and waste valve

During the period of water main cleaning on your street, you should:

  • Avoid using water, including hot water, as this will likely draw discoloured water into your home’s pipes; and
  • Avoid washing clothes or doing dishes as discoloured water may cause stains.

After the water main on your street has been cleaned you should:

  • Run the cold, hard (unsoftened) water tap closest to your water meter (usually located in the basement) until the water is clear. Alternatively, if your garden hose provides hard water, you can irrigate your lawn or garden until the water is clear.
  • If the water remains discoloured after 10 minutes of flushing, please turn off the tap, wait 60 minutes, and repeat the 10-minute flushing process again. If your water does not clear after 2 hours, please contact the City of Guelph Water Services Division at 519-837-5627 for assistance.
  • Call Water Services at 519-837-5627 if you have no water or low water pressure after the water main cleaning has been completed.
  • If your water is clear, turn on your water treatment or softening devices, flush each tap if necessary to remove discoloured water from your pipes, flush your toilets during normal use to remove discoloured water from your toilet tank, and resume normal use including drinking the water and clothes washing.

Where does the sediment in the water mains come from?

The sediment present in Guelph’s water mains consists mostly of a combination of iron and manganese oxides. When these fine particles are mixed and suspended in water, they cause discolouration that is often described as brown, red, yellow or black water.

Iron and manganese oxides are formed when chlorine combines with the dissolved iron and manganese minerals naturally present in Guelph’s groundwater. These oxides are heavy and will settle-out on the bottom of water main piping during periods of normal water use. The settled particles are stirred up to form discoloured water when a larger demand for water use occurs or when maintenance is being performed on the system.

Can I drink the water?

The City recommends that customers do not consume discoloured water, but wait instead until the normal clarity of their water returns.

Samples of discolored water have been analyzed and although it may not smell, taste, or look pleasant, tests have shown that it is safe. Drinking small quantities of discoloured water is not likely to cause a health problem. The most common element in discoloured water is iron, a nutrient found normally in many foods. For customers with iron storage disorders, additional iron in drinking water could present a health risk. These individuals should avoid drinking discoloured water and consult their physicians for additional information.

In compliance with Provincial regulations, the City continuously maintains a disinfectant residual in all water supplied to ensure customer safety. We work closely with the Wellington-Dufferin-Guelph Health Unit on all matters pertaining to the safety of municipal drinking water. Please call the Wellington-Dufferin-Guelph Health Unit at 519-821-8370 if you require more information on the health effects of discoloured water.

If, for any reason customers feel ill, we recommend you consult your family physician.

What should I do if my laundry becomes stained by discoloured water?

If you are washing clothes and receive discoloured water, stop the cycle while it is tank is full and wait until clear water is available to finish. If the spin cycle has finished, then keep the clothes wet and rewash them when clear water is available. If you wash your stained clothes using a commercial rust remover, then follow the directions on the rust remover label to avoid damaging your clothes.

Is flushing my pipes to remove discoloured water costing me money?

At current water and sewer rates, a customer in Guelph pays approximately 3 cents for every minute that a tap runs.