1. Groundwater wells
Make sure your well head (top of the well) is above the ground’s surface where it will not be at risk of being flooded. You should also have a good seal around the well where the well casing emerges from the ground to stop surface water running down the side of the well casing.
Keep the well cap closed tightly to prevent surface water, animals or contaminants from getting into the well. Make sure that your well also has a backflow preventer which will stop pumped water flowing back into your well.
We also recommended that you filter and treat well water before you drink it. Well water can easily be tainted by contamination sources hundreds of metres away from the well.
You can find more useful resources in this pamphlet from the Ministry of Health and from the HealthEd website.
1. Well cap - tightly installed and sealed between the casing and any hoses/cabling going down into the well
2. Well casing - ensure casing is above any potential flooding
3. Concrete apron - seals the casing and the surrounding ground. The seal should slope away from the bore to stop surface water pooling around the bore casing. There may also be a bentonite seal around the casing, depending on the drilling method used
4. Backflow preventer - stops contaminants siphoning back into your well
5. Sample point - it would be useful for your well to have a sample point
Don't
1. Store rubbish, pesticides, compost, fertilisers and petro-chemicals near a well head
2. Locate offal pits, septic tanks and other contaminant sources near any well
Do
1. Keep the area around the well clear of animals (e.g. via fencing around the area), pesticides, fertilisers, compost, rubbish, vegetation and effluent
2. Have a raw water sample point so you can quickly test the water. This will help if you need to check whether contamination is at the well, a treatment system failure or is a contamination in the pipes leading to drinking water taps
3. Maintain the well - earthquakes and ground movements can damage a well head
4. Look into the history of your land in case any existing or historical activities nearby may affect well water quality
5. Find out how your well has been constructed and operates so that you can preserve it. Ask your regional council or driller for more information
Well construction – in particular it's worth finding out:
- When the well was drilled,
- What geology the well is located in,
- How deep the well is,
- How it was constructed,
- The type of pump and depth at which it is set within the well,
- Information on the pumping rate and water level drawdown
These details are recorded in a driller’s log prepared at the time the well was drilled and will help you understand where water is coming from, what type of geology it flows through, and if the well has been constructed correctly to prevent contamination from entering the well.
Unwanted wells must be properly decomissioned or sealed to prevent contamination entering groundwater.
If you do not decommission an unwanted bore on your property you can be fined. Your local driller can provide advice on decommissioning and keeping your well secure.
2. Stream, river, or spring
It can be hard to prevent streams, rivers and springs becoming contaminated by factors further upstream that you don’t know about.
To reduce bacteria risk to your surface water supply collect your water as close as possible to origin of your source. For example in headwaters of a river or stream where there are less impacts from humans or animals. Fence off the area surrounding your water collection point to stop animals from entering your water supply.
Because streams, rivers and springs are easily accessed by animals or impacted by upstream activities, we recommend that you filter and treat water before drinking.
You can find more information on the HealthEd website.
3. Roof rainwater collection tank water
We encourage you to:
- Read the Ministry of Health's guidelines on how to correctly install and protect roof rainwater collection supplies
- Check your roof has been painted with lead-free paint and does not have lead flashings
- Check your collection system has gutter mesh, plastic pipe, and gutters approved for rainwater collection
- Keep your water tank covered and trim all vegetation overhanging your roof to stop animals, leaf litter, and debris from accessing the tank and roof
- Have your tank inspected annually and if necessary cleaned by a qualified tank cleaner
