Water quality testing and sampling in agriculture

Water quality can vary across sources — including dams, bores, creeks and tanks — and change throughout the year due to rainfall, runoff, evaporation and contamination. 

Understanding what’s in your water helps you make better decisions about how and where to use it.

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Video transcript

Farm Water Series - Water Quality

in this farm water video series we've

already spoken about the importance of

having enough water to meet your needs

equally important is water quality

so water quality can vary widely

depending on the source the time of the

year and even recent conditions such as

drought or major storm events

with the recent drought both water

quantity and quality were real issues

poor water quality means that livestock

are likely to drink less and if water

intake goes down feed intake also goes

down and the risk of animal health

issues increases

a whole range of things can affect water

quality and its suitability for

livestock

this can include ph salt levels

algae and contamination even from dust

or manure or feed and even water

temperature can all affect water quality

all of these things have an impact on

the palatability of the water making it

less attractive to stock and thereby

reducing consumption

a water test can help determine the

suitability of water for a range of uses

or if it's going to cause issues so is

it suitable for for livestock is it

suitable for stock and domestic use on

your gardens things like that

a water test can give us some clues but

it won't give us all the all the answers

it you know it won't pick up on things

like water temperature

dust odour things like that

that's when it comes back to really you

know livestock skills observation and if

you suspect there is

a water issue

stocks showing a reluctance to drink the

best thing to do there is to provide

alternative water source and then

observe to see what happens

one of the key things for improving

water quality on your farm where

possible try and maintain ground cover

in the paddock and particularly try and

maintain

really good levels of ground cover in

those drainage lines that feed into the

dams

by keeping those drainage lines well

grassed up that'll tend to act like a

filter for the water as it comes into

the dam and filtering out you know soil

and

and sediment and manure and things like

that

so here we're looking at an example of a

dam on a property that has been fenced

off to promote high water quality

the fenced off area means that the area

around the dam is well grassed up so

that acts like a filter but also

importantly the fence keeps stock out of

the dam so therefore ensuring the water

doesn't get fouled up

this dam it's a big dam it's a key dam

on the property and what they've done

here is they've set up a system with a

with a solar pump that pumps the water

up to some header tanks on a hill and

that header tank then feeds water to a

network of troughs throughout the

property

the dam is is providing the property

with a reliable source and a large

volume of high quality water even in

drought conditions or in dry conditions

and that high quality water

through the reticulation system the

owners are able to then pump and

distribute that high quality water

throughout the property

sometimes you know we can have a water

source that is really good one day and

the next day can be contaminated and

thereby rendering it unsuitable for

stock

when dams become contaminated with all

that debris and manure you'll notice

that the water goes off it has quite a

dark appearance and it actually has

quite a bad smell which really puts the

stock off from drinking it makes it

quite unpalatable

during dry periods also dams can become

contaminated by algae algae affects the

taste and the smell of water making it

less palatable to livestock

if you suspect that you've got blue

green algae which we know is toxic to

livestock a separate water test can be

done to determine its presence

dams that are contaminated either with

debris or manure or algae generally one

of the first steps is to try and aerate

that water and that that can be simply

done by putting a fire fighting unit on

the bank and just reticulating the water

over

water quality has a positive correlation

with livestock performance and so if

you're looking at

ways to improve water quality on your

farm or if you're trying to deal with a

contamination issue contact your local

land services advisory officer for

specific advice or help in addressing

water quality or any contamination

issues you might have on farm

[Music]

Why water quality matters

Water quality affects:

• livestock health and performance
• crop growth and nutrient uptake
• soil structure and salinity
• equipment longevity and maintenance
• household use and safety.

Poor water quality can reduce feed intake, slow weight gain and increase disease risk in livestock. For example, cattle drinking clean water from a trough may gain up to 20 per cent more weight than those drinking directly from a dam. Saline or contaminated water can also damage irrigation systems and reduce soil productivity over time.

What to test for

Water testing can identify a wide range of chemical and physical attributes. Common indicators include:

• salinity (electrical conductivity)
• pH (acidity or alkalinity)
• turbidity (cloudiness from sediment or algae)
• temperature
• nutrient imbalances (for example, nitrogen, phosphorus, chloride, iron)
• toxic residues or heavy metals
• blue-green algae and pathogens.

If you're using water for livestock, irrigation or domestic purposes, it's important to test for the attributes relevant to that use. For example, high sodium or chloride levels may be tolerable for sheep but unsuitable for crops or household use.

What’s in my water? 

Understanding aquatic growths and contaminants

Water sources—especially dams and tanks—can host a surprising variety of aquatic growths, including algae, microscopic organisms, and free-floating plants. These growths become more noticeable during dry spells or hot weather, when water levels drop and nutrient concentrations rise.

Key points to consider:

• Algae is natural: It exists in most environments and can be harmless in small amounts. However, under certain conditions, it can bloom rapidly and become toxic.
• Blue-green algae (cyanobacteria): Unlike typical algae, this behaves more like bacteria and can produce toxins harmful to livestock, humans, and wildlife.
• Triggers for growth: Warm temperatures, sunlight, nutrient runoff (especially from paddocks), and stagnant water all contribute to excessive growth.
• Impacts: Algae can block irrigation systems, cause unpleasant odours and tastes, and make water visually unappealing. In severe cases, it can lead to livestock illness or death.
• Treatment options: These include mechanical removal, aeration, and chemical treatments—though prevention through regular monitoring and runoff control is often more effective.

Maintaining healthy water means staying alert to changes in appearance, smell, and clarity. Regular sampling and proactive management can help keep your water safe and usable year-round.

If you suspect blue-green algae

Contact your local Local Land Services district veterinarian or agriculture officer.

Algae testing requires a separate procedure and should be handled promptly.

How to collect and test water samples

Follow these steps to ensure accurate results:

• choose the right test kit for your intended use
• read the instructions carefully before sampling
• use clean containers — microbiological test bottles must be in date and contain a chlorine neutraliser
• collect samples from representative points (for example, troughs, dam surface, bore outlet)
• store samples correctly and deliver to the lab within 24 hours
• use an accredited laboratory for analysis.

What to do with the results

Once you receive your test results:

• compare them against recommended thresholds for livestock, irrigation or domestic use
• identify any risks or limitations
• consider treatment options (for example, filtration, aeration, alternative sources)
• keep records to track seasonal changes and support future planning.

If water quality is poor, you may need to:

• switch to troughs instead of open dams
• rotate water sources to reduce pressure on any one supply
• manage livestock access to reduce fouling and erosion
• install shade or cover to reduce algae growth and evaporation.