Wednesday, May 22, 2019 - 12:00 PM

Hydrant Flushing Begins for 2019

hose releasing water

As part of our ongoing commitment to safe drinking water, our Water and Wastewater team normally conducts a unidirectional water main flushing program between May and October of each year. This maintenance activity ensures we continue to provide the highest quality drinking water within our water distribution network.

Water is delivered to your home through a system of pipes.

Raw water is drawn from one of three sources in St. John’s – Windsor Lake, Bay Bulls Big Pond, and Petty Harbour Long Pond. While we are very lucky in St. John’s to have some of the most pristine water sources in the world, the water still must be treated before it is ready to be distributed to your home. Located at each water source is a water treatment facility where raw water is treated and tested, to rigorous national standards, before it enters the water distribution system. From there it travels through a network of pipes throughout the City, to your home and to your tap.

Learn more about water treatment processes by watching this video on the Petty Harbour Long Pond Water Treatment Facility.

What is the purpose of hydrant flushing?
Over time, pipes in a water system will develop a build-up due to corrosion products, treatment byproducts and other natural sources. While this is normal and expected, it does require managing to ensure it does not negatively impact supply to your home.

This is where hydrant flushing comes in.

The flushing starts close to the source (i.e. water treatment plant) and moves outwards, in order, ensuring that clear water is always being used to flush the mains.

This flushing is most effectively performed using a method called “unidirectional flushing”, where water mains throughout the network are flushed in a specific sequence with the water being discharged from a fire hydrant. Each sequence is designed to control flow, by closing specific valves to force water movement in one direction along a set path, ending at the open hydrant(s). This method of flushing increases the speed of the water flow in the targeted water mains which produces a scouring action, resulting in the removal of sediment deposits and build-up, leaving a cleaner pipe with better flow behind.

How long does it take to flush the water mains on each street?
It takes about 30 to 60 minutes to flush the water mains on each street. After the flushing, the water can be cloudy for up to four hours.

Can I use my water when you are flushing the water mains in my neighbourhood?
When you see flushing being carried out on your street, you should avoid using water for any purposes that require clean water. This would include preparing food and beverages, medical and dental procedures or laundry. You should also avoid using your hot water system to minimize the amount of sediment drawn into your hot water tank.

How can I clear my water?
Turn on a cold water tap and let the water run for a few minutes. We recommend using the cold water faucet on a bathtub. Do not choose a tap that has a water filter connected to it, or the sediment may clog your filter. Do not use a hot water tap because it could draw sediment into your hot water tank.
Catch some water in a light-coloured cup or container to see if it is clear. You can use your water if it is clear.

If the water does not clear in 15 minutes, wait 30 minutes and try again. If the water is still discoloured after three to four hours, please call Access St. John's at 311 or (709) 754-CITY (2489) and a City representative will contact you.

How will I know you are doing flushing in my neighbourhood?
Our crews post signs in the neighbourhood where flushing is occurring and we post an advisory on the City’s website.

Flushing is generally conducted between 8 a.m. and 4 p.m., Monday through Friday. While the hydrants are open, the residents in the neighbourhood may experience discoloured water or a small drop in water pressure, however, your water service should not be interrupted. If you have no water pressure, please notify Access St. John's at 311 or (709) 754-CITY (2489) as soon as possible.

Should I be worried about Manganese?
No. Manganese is an essential nutrient that is found in air, food, consumer products, soil and drinking water. Manganese is always in water, but high levels of this element cause the water to be discoloured.

In 2018, the City experienced unusually high levels of manganese from one of its water sources, Petty Harbour Long Pond. The other two water sources did not experience these high levels. At the time, in consultation with Environmental Public Health at Eastern Health, the City was able to assure residents on the Petty Harbour water supply that the manganese levels reported were only a concern to infants under 1 year of age; more specifically, infants who would be getting water through mixed formula and cereals, or given water directly to drink. At the time, these people were specifically advised to use an alternate source of water.

Infants who were breastfed or fed premixed formula were not at risk, except where they were being given water to drink – in which case they would also require an alternate source of water. Older children, adults and seniors would not experience health concerns at the reported levels of manganese.

The City has since altered its water treatment process at the Petty Harbour plant such that, if levels were to rise again, we would be better able to reduce manganese in the treated water before it enters the water distribution system.

While there may be manganese in the sediment that is removed from our water mains with the flushing process, the water being delivered to your home is clear, tested and meets all national guidelines for manganese and many other naturally occurring elements.

Watch our video on hydrant flushing.