Collecting and packaging water samples for testing by Grow Help Australia

What we test for

Our testing detects a wide range of species but won't determine whether those detected species are pathogenic. However, our testing will determine whether there is a pathway for pathogens to enter your nursery or hydroponic system through irrigation water. If a pathway is open, it indicates that plant pathogens can be irrigated onto plants.

We test for 4 groups of microorganisms:

• general bacteria
• general fungi
• oomycetes
• Phytophthora-specific oomycetes.

To test for all 4 groups of microorganisms, we need 2 litres of water for each sample. This volume is essential, because pathogens are not evenly distributed in the water.

Our testing can detect pathogens down to 1–2 spores per litre, but only if for each test we have 500 millilitres of water. If we receive less than 2 litres of water, the number of tests we can complete is reduced. If we receive only 1 litre, we will test for general fungi and oomycetes only.

Cost of tests

Each test is charged at the fungal and bacterial plate culturing test price.

The following price variations apply for production nurseries:

• For a levy-funded project, testing is free for up to 3 water samples twice a year until the end of 2030.
• Testing is free for your first 6 plant samples submitted per year. For your next 12 samples each year, you will receive a 50% discount.

For more information, refer to the current information on fees and charges.

Contaminated and raw water

If a sample is obviously contaminated with soil, algae, organic matter or other 'floaties', we do not test for bacteria. The level of bacteria in these samples is likely to be extremely high.

There is limited value in testing raw dam, creek or river water without also testing a sample of water after it has been disinfested. Irrigation water taken directly from a dam, creek or river will always have a high level of microorganisms, so the pathway for plant pathogens to enter your crop is always open.

Number of samples

If you are submitting more than 3 water samples at once, please email growhelp@dpi.qld.gov.au. Testing this many water samples can be time-consuming and we need to arrange suitable timeframes.

Step 1: Prepare collection containers

• For sampling, you will need brand new plastic drinking-water bottles—please don't use glass bottles.
• Bottles should be 1–1.5 litres. Bottles this size will be less affected by changes in temperature during transport.
• You can buy the bottled water from any supermarket or general store. Ensure you buy still (non-sparkling) water.
• Just before sampling, pour out the bottled water (for example, into a jug or container for drinking or other use).
• Do not drink from the bottles—this will contaminate the samples.
• Make sure the lids stay clean—if you drop a lid on the ground, do not use it.

Step 2: Collect samples

Collect your samples on the day you are sending them to us or dropping them off for testing.

Take samples from 2 points in the system that are easily accessible:

• a pre-disinfestation sample
• a post-disinfestation sample.

The pre-disinfestation sample will provide baseline information on how many microorganisms are in the water. By comparing this with the post-disinfestation sample, we can better assess the efficacy of the disinfestation system.

Pre-disinfestation sample

Collect water immediately before disinfestation occurs.

• If possible, take the sample directly from the pump/intake. If this is not possible, collect the sample as close to entering the disinfestation system as possible.
• If disinfestation occurs in a tank, collect the sample before the disinfectant is added to the tank.

If collecting the sample from a dam:

• Collect water from a different point of the dam for each water bottle (if sending more than 1 bottle).
• If possible, use a pole or other tool to collect water away from the edge.
• Collect water from:
  • below the surface (but not from the bottom)
  • as close to the pump/intake as possible.
• Take care when collecting samples to avoid injury.

Post-disinfestation sample

• Collect water immediately after disinfestation, preferably before it is moved to a holding tank or used for irrigation.
• If disinfestation occurs in the holding tank, collect your sample after the appropriate contact time has lapsed.
• If you suspect water is getting reinfected after disinfestation, collect samples at different points in the irrigation system to help identify where the problem is. For example, you could collect samples from:
  • storage tanks
  • before and after irrigation lines split
  • where water is applied to plants.

Step 3: Register samples for testing

Complete the online form to register your samples for testing.

The form includes questions about your disinfestation system. The information you supply will help us interpret results and provide more accurate recommendations for your irrigation system. Over time, trends may emerge that allow for industry-wide recommendations; however, your information will always be de-identified.

You may be asked for information about:

• raw water source(s)
• the type of disinfestation system or systems used, including pre-disinfestation filtration
• the post-disinfestation concentration of the disinfectant, in parts per million (for example, for chlorine-based systems)
• the dosage rate and any other dose-related information relevant to the disinfestation system (for example, for chlorine-based systems)
• where the samples were collected, for example
  • pre-disinfestation water directly from the dam, the creek or a tap immediately before disinfestation
  • post-disinfestation water from a tap immediately after disinfestation.

Step 4: Package samples

• Do not cool, freeze or heat the samples after you collect them or in transit, as this can alter the microbial population.
• Label each bottle with the:
  • collection date
  • sample identifier you listed in the online submission form, for example 'Sample 1—Dam, pre-disinfestation'.
• Print the email confirmation you received after completing the online form. Include this in your package.

Step 5: Send samples

Check our address and drop-off location and mark these correctly on the package.