Novacoil and French drains for wet lawns, retaining walls and foundations, installed by a certifying drainlayer.
Some drainage problems are easy to see, like water running off the roof. Others sit just below the surface, where groundwater builds up with nowhere to go.
Much of Northland sits on clay that drains slowly, so water soaks into the topsoil and then has nowhere to go. Subsoil drainage is often the fix for all of these problems. We install subsoil drains across Northland for homes, baches and lifestyle blocks.
A subsoil drain is a trench with a perforated pipe, usually Novacoil, laid in the bottom and surrounded by drainage metal. Groundwater seeps into the metal, into the pipe and is carried away to a safe discharge point. We use Novacoil with a filter sock as standard, which stops fine soil and silt getting into the pipe and blocking it. Once the trench is backfilled, the drain sits out of sight and keeps working after every downpour.
Subsoil drainage deals with water in the ground, while stormwater drainage deals with water on the surface and from the roof. Many properties need both, and they often connect into the same system. Our stormwater page explains the surface water side. Stormwater drainage →
Every subsoil drain needs a proper outlet. Depending on your property, that might be the council stormwater system, a soak pit or another approved discharge point. In Whangarei, work on private stormwater systems has to be done by a licensed drainlayer, and water can’t be directed onto a neighbour’s property.
A small retaining wall, holding back no more than 1.5 metres of ground and with no extra load above it, doesn’t need a building consent as long as it includes groundwater drainage. For other subsoil drainage work, we can tell you whether your job needs a consent. If it does, we’ll factor that into the quote and timing.
Every site is different, so we quote each job individually. The main things that affect the price are:
Quotes are free in Whangarei and the surrounding area. We’ll look at where the water is coming from before we quote, so the fix matches the problem. Your quote will set out exactly what’s included.
Subsoil drains need very little attention once they’re in. Keep the outlet clear of leaves, soil and debris so the water can get out. If wet patches start coming back, the drain may be blocked or damaged, and a camera inspection can find the problem without digging. Drain camera inspections →
Can’t see your question? Call us on 021 0236 9667.
It’s usually groundwater sitting on clay soil, water running off a slope above, or both. Downpipes emptying onto the ground can make it worse. A subsoil drain collects the water below the surface and carries it away, and we can check whether stormwater is part of the problem too.
A French drain is the trench itself, filled with drainage metal to collect water. Novacoil is the perforated pipe laid in the bottom of the trench to carry that water away. Most subsoil drains use both together.
Almost every retaining wall benefits from drainage, because water building up behind it adds pressure. For small walls, groundwater drainage is also one of the conditions for not needing a building consent. If an existing wall is seeping, a drain at the base can often help, even if we didn’t build the wall. A wall that’s leaning should be checked by an engineer first.
Tell us where the water is and what you’ve noticed. Photos taken during or after heavy rain are the most useful thing you can send, because they show where the water sits.
We reply to every enquiry within one working day.
021 0236 9667