Water Quality

When you fill up your glass with water from your tap, you can be assured that Hamilton’s drinking water is safe to drink. Standards for drinking water quality are set and legally enforced by the Safe Drinking Water Act. The City of Hamilton’s drinking water consistently meets all Ontario Drinking Water Quality Standards. The SDWA focuses on:

  • treating and testing drinking water
  • public access to information and notification of adverse water results

Water samples are collected Monday to Friday by City staff from approximately 111 locations, and are analyzed for total coliform, E. coli and heterotrophic plate count. Chlorine levels are measured in the distribution system 7 days a week.

Water quality reports

2018 Annual Drinking Water Reports covering the period of January 2018 to December 2018:

March 2017

Common concerns about water quality

Water main repairs, construction and other maintenance work in an area can cause some rust and scale products, which normally adhere to the inside of the water main, to break away. Open fire hydrants can also cause this. The discoloured water is safe to drink, but the water may appear dirty or may stain your laundry.

If your water is yellow or rusty coloured, run your cold water tap for five to 10 minutes, or until the water clears. If the water does not run clean, call 905-546-2489.

Water naturally varies in taste and odour at different times of the year.  If may smell or taste different, especially late in summer or early fall. This is usually the result of algae growth in the lake, partially caused by the change of the season. Different types of algae can cause water to taste and smell musty. Although the taste and odour can be unpleasant, it is not considered to be a public health problem. Refrigerating the water helps eliminate the odour and adding lemon slices helps remove any bad taste.

Water may also taste stale if it has been sitting in the incoming pipes for too long. Flushing out the pipes in your home by turning on all of your taps at the same time for a few minutes may get rid of the bad taste.

Water hardness is calculated using the the calcium and magnesium concentration in the water. It is expressed as mg/L calcium carbonate or in Grains per gallon (imperial or US). One grain per imperial gallon equals 14.25 mg/L calcium carbonate and one grain per US gallon equals 17.1 mg/L calcium carbonate.

How hard is Hamilton water

The Hamilton potable water is considered to be "medium" hard. The water hardness value is about 120 mg/L calcium carbonate  or about 8.4 grains per imperial gallon.

The following values are typical values for the drinking water systems. The Carlisle results listed are the average of all four wells.

Drinking Water System Hardness in mg/L Calcium Carbonate       Hardness in Grains per Imperial Gallon  
Carlisle 390   27.4   
Freelton  360   25.3
Greensville  500   35.1 
Lynden  51   3.6