1. Check if your private water supply pipe is leaking
If there is a significant amount of groundwater on your property, this may be due to a leaking water pipe. Follow the steps below to help determine whether this is the case:
i. Turn off all taps
ii. Read your water meter
iii. Re-read water meter after a few hours
iv. If the water meter registers water usage, a leak on the water supply pipe may be the cause of groundwater problems.
v. If a repair is required, contact a plumber or drain layer.
If required, Council has a guide on how to read your water meter. Please refer to Council’s website (
www.ccc.govt.nz) or contact a member of the Technical Services Team on 941 8999.
2. Check if an old artesian bore is leaking
Prior to the public water supply being available in Christchurch, many properties had their own artesian bore to supply domestic water. These bores were mostly capped near the ground surface when the public water supply system became available. The recent earthquakes have broken the top of some of these bores, with water now seeping out above ground onto properties. Follow the steps below to help determine whether your groundwater problem is associated with a broken artesian bore:
Slowly stir any muddy waters around or look for water bubbling up until you can locate a likely source of water seepage.
Dig down about 0.5m to see if you can locate a vertical leaking pipe.
If a leaking pipe is found, discuss with a plumber or drain layer the feasibility recapping it. Note however this may only be a short term fix if the bore pipe is in poor condition. In the long term, residents should consider engaging a specialist well sinking or well drilling firm to grout and seal the damaged artesian bore.
3. Check If Your Private Storm Water System Is Working
Your groundwater issue may be associated with a broken or blocked stormwater system on your property. If necessary, obtain a drainage service plan from the Council, then determine if your property’s stormwater system outfall is to:
a) the street kerb
b) a piped system
c) an open drain
d) a soak-pit
e) a land surface
Depending on the type outfall for your stormwater system on your property, please refer to the following steps:
a) Street kerb outlets
i. Run garden hose water into the ground outlet point of each roof guttering down-pipe on your property to see whether the water comes out at the street. You may have to wait several minutes for this to happen.
ii. If very little or no water is reaching the roadside kerb or your groundwater has worsened after this test, damage or a blockage to your stormwater pipes are likely. Engage a drain layer to address this.
b) Piped systems
i. Locate the first sump lid downstream of your property and open the lid.
ii. Run garden hose water into the ground outlet point of each roof guttering down-pipe to see whether there is water coming out into the sump chamber. You may have to wait several minutes for this to happen.
iii. If very little or no water is reaching the sump chamber or your groundwater has worsened after this test, damage or a blockage to your stormwater pipes are likely. Engage a drain layer to address this.
c) Open drains
i. Locate the pipe outlet from your property into the open drain.
ii. Run garden hose water into the ground outlet point of each roof guttering down-pipe to see whether there is water discharging into the open drain. You may have to wait several minutes for this to happen.
iii. If very little or no water is reaching open drain outlet, and your groundwater has worsened after the test, damage or a blockage to your stormwater pipes are likely. Engage a drain layer to address this.
d) Soak-pits
i. Locate the soak pit on your property.
ii. Run garden hose water into the ground outlet point of each roof guttering down-pipe and see whether there is any signs of water starting to pond on the surface or your existing groundwater problem is worsening. You may have to wait a few hours for this to happen.
iii. If your soak pit is overflowing, with water ponding on the surface, or your groundwater problem has worsened after this test, your soak pit may not be functioning property. Engage a drain layer to address this.
e) Surface discharges
If your stormwater system is reliant on surface discharges (i.e. no formal stormwater system), the ground onto which stormwater would normally drain into may no longer be permeable due to liquefaction or soil layers being unsettled as a result of the earthquakes. You may wish to consider one or both of the following options:
i. In the long-term, it is advised that a formal stormwater system be established for your property and to contact Council’s Duty Building Planner regarding this on 941 8999.
ii. In the short-term, try replacing the upper 150mm of topsoil within the soakage area on your property, with free draining topsoil.
4. Check if your private sewer pipes are leaking
Your groundwater issue may be associated with broken or blocked sewer pipes on your property. If necessary, obtain a sewer service plan from the Council and follow the steps below:
i. Check if your groundwater smells and is predominantly in the area of your sewer pipes.
ii. If a smell is evident, arrange to have your pipes inspected further and for advice on repairs required.
5. Check for leaks from your septic tank
Some properties have a septic tank as part of their sewer system, as opposed to being connected to the Council’s sewer network. Follow the steps below to help determine whether your groundwater issue may be associated with your septic tank:
i. Locate the septic tank on your property and check for obvious sewerage smells.
ii. If your groundwater smells and is predominantly in the area of your septic tank, the tank may be broken.
iii. Engage a drain layer to investigate further and to advise the best course of remedial action. Should a connection into the Council sewer system be considered, please contact Council’s Duty Building Planner on 941 8999.
6. Check for local land surface depressions and hollows
The ground profile in and around your property may have changed as a result of the earthquakes, with depressions and hollows now formed on the surface. These may hold water during rainfall events and take some time to drain away. You may wish to consider one or both of the following options to address this:
i. Re-instating the original ground profile by back-filling depressions and hollows with top soil. Care must be taken when undertaking this work, so as not to inadvertently divert surface stormwater into your neighbours property or under your house. You may also need to liaise with your neighbours before undertaking this work to determine the profile of their land. Note there are limitations on backfilling on properties – Council’s Duty Building Planner should be contacted regarding this on 941 8999.
ii. Engage a drain layer to advise on the best course of action in terms of installing a new stormwater system that can cope with your new ground conditions.
7. Check the ground profile of your neighbours land
The ground profile of your neighbours property may have changed as a result of the earthquakes. If you are experiencing new surface water runoff from your neighbours property, please contact them in the first instance. You may also wish to contact a drain layer to advise whether installing a new stormwater drain to intercept this new surface water on your property is feasible.
8. Check for new springs
Your groundwater problem may be caused by a new natural spring that has been created as a result of the earthquakes. These springs may be temporary or long-term; their lifespan is largely unknown. If other tests have already been completed and proved unsuccessful, follow the steps below to check for new springs:
i. Identify any signs of water bubbling up.
ii. Engage a drain layer to investigate further and to advise the best course of action.
Disclaimer
This information is provided by the Christchurch City Council for general information purposes only and does not constitute geotechnical or engineering advice. The Christchurch City Council does not warrant that the information provided will be suitable to your particular circumstances and you should seek geotechnical or engineering advice.
