Water contaminants

Water testing is essential to determine whether drinking water is safe and if any treatment is necessary. Laboratory reports often contain technical terminology and units of measurement that may be difficult to interpret. Familiarity with these elements supports informed decisions regarding water quality and health protection.

Most laboratory results include multiple parameters, which are assessed against the New Brunswick Drinking Water Quality Guidelines (PDF 393 KB) to verify compliance with safety standards. To learn more about the health-based and aesthetic limits for drinking water, consult those guidelines.

The Maximum Acceptable Concentrations (MAC) is a level that has been established for certain substances that are known or suspected to cause adverse health effects. 

The Aesthetic Objective (AO) is established for parameters that may impair the taste, smell, or colour of water; or which may interfere with the supply of good quality water. They do not cause adverse health effects. 

E. coli

• common sources: contamination from sewage, animal waste or surface water 
• MAC: none detectable per 100 mL 
• health risk: serious illness including nausea, vomiting, diarrhea
• treatment: UV light disinfection systems (NSF Standard 55 Class A), chlorination (disinfects plumbing systems), ozone treatment, distillation 

Arsenic

• MAC: 0.01 mg/l
• health risk: long-term exposure may increase cancer risk
• treatment: reverse osmosis, distillation, adsorption or anion exchange

Boiling your water does not remove arsenic.

Lead

• source: old pipes, solder or fixtures
• MAC: 0.005 mg/l
• health risk: affects brain development in children; kidney and nerve issues in adults.
• treatment: replace plumbing, use reverse osmosis or certified filters (NSF standard 53)

Boiling your water does not remove lead. 

Uranium

• MAC: 0.02 mg/l
• health risk: kidney damage from long-term exposure.
• treatment: reverse osmosis, activated alumina, or anion exchange

Boiling your water does not remove uranium.

Iron

• AO: 0.1 mg/L
• effect: stains, black particles, metallic taste
• treatment: aeration, greensand filtration, oxidizing filters, reverse osmosis

Boiling your water does not remove iron. 

Manganese

• MAC: 0.12 mg/L
• AO: 0.02 mg/L
• health risk: neurological development and behaviour (infants are more vulnerable) 
• other effects: stains, black particles, metallic taste
• treatment: aeration, greensand filtration, oxidizing filters, reverse osmosis

Boiling your water does not remove mangenese. 

Nitrate

• MAC: 45 mg/L (or 10 mg/L reported as nitrate-nitrogen)
• health risk: dangerous for infants under six months
• action: find and fix the source of contamination
• treatment: Ion exchange, reverse osmosis

Boiling your water does not remove nitrates. 

Antimony

• MAC: 0.006 mg/L
• health risk: high levels may cause nausea, vomiting or diarrhea
• treatment: coagulation and filtration, reverse osmosis or distillation.

Boiling your water does not remove antimony. 

Private well water can be affected by a variety of naturally occurring substances and human activities. Some contaminants are invisible, tasteless and odorless, while others may affect the taste or smell of water. Regular testing and proper treatment are essential to ensure safe drinking water. 

Sources

Salt is naturally present in groundwater, but common causes of elevated levels can be: 

• road salt 
• seawater intrusion near coastal areas 
• septic systems 
• underground salt deposits  
• water softeners  

Health and household concerns

High levels of sodium and chloride in household water can raise health and maintenance concerns. For individuals on low-sodium diets, elevated sodium levels may pose a health risk. Meanwhile, high chloride concentrations can lead to corrosion of plumbing systems, damage household appliances and negatively affect the taste of drinking water.  

To help manage these risks, guidelines recommend chloride levels at or below 250 mg/L for aesthetic purposes, and sodium levels at or below 200 mg/L for taste. For those with sodium-restricted diets, a much lower limit of 20 mg/L is advised.

The only way to know levels is through accredited laboratory testing. 

Causes and solutions 

1. Road salt contamination: seasonal testing is useful. Ensure proper well location and casing and a licensed driller may recommend repairs or a new well. 
2. Naturally occurring salt: found in some regions due to ancient seawater deposits. Treatment may be the only option. 
3. Saltwater intrusion (coastal wells), caused by proximity to the ocean or over-pumping freshwater aquifers: 

• reduce water consumption
• practice water conservation (low-flow fixtures, rainwater collection, only run full loads in washers)  
• consider treatment options such as reverse osmosis or distillation, typically for drinking water only 
• in severe cases, drilling a new well may be required, along with decommissioning the old one

A “rotten egg” smell is usually linked to hydrogen sulphide gas or sulphate-reducing bacteria in the water supply. 

Possible causes 

Hydrogen sulphide in drinking water can originate from both natural and household sources. In New Brunswick, it may occur naturally in groundwater due to the breakdown of organic matter in certain rock formations. Within homes, it can be produced by reactions in hot water heaters—particularly when magnesium rods interact with sulphates—as well as by clogged drains or organic buildup in plumbing systems.  

Additionally, water treatment devices such as filters or softeners may contribute to the issue if not properly maintained.

How to identify the source 

• persistent smell in both hot and cold water: likely hydrogen sulphide in groundwater 
• smell in treated water only: likely the treatment device 
• smell only in hot water: likely the water heater 
• smell that lessens after running the tap: likely sulphate-reducing bacteria 

Treatment options 

Residents can install systems such as chlorination units, sand or carbon filters, manganese greensand, aeration systems or other adsorption media to improve water quality.  

In hot water heaters, replacing magnesium rods can help reduce hydrogen sulphide production. Shock chlorination of the well and plumbing system is another effective method. It’s important to note that testing for hydrogen sulphide requires special sampling bottles and rapid processing—this service is available through RPC (Research and Productivity Council). 

Changes in taste, colour or odour may indicate a water quality issue. In such cases, testing is strongly recommended. Below are common symptoms, their possible causes and treatment options:

Not all systems work for every contaminant. Certification and proper maintenance are crucial. 

Monitoring, testing and treatment are essential to protect health and to prolong the lifespan of plumbing systems and household appliances. For detailed information on acceptable levels of contaminants and aesthetic factors, see the Drinking Water Quality Guidelines (PDF 393 KB).

Test results should be compared to provincial guidelines to ensure water quality standards are met. Copies of each report ought to be retained to track changes over time, and results should be shared with new homeowners or well users. In cases of uncertainty, the testing laboratory or the Healthy Environments Branch can provide further assistance.