Civilmart’s Guide to Concrete Soakwells

No matter where you live having the right stormwater drainage system is something that needs to be front of mind. However not every drainage system is going to work in every terrain. This is way soakwells can be the best option over on the west coast of Australia.

These large underground tanks with their downward angled drainage holes (louvres) play an integral role in collecting runoff from gutters, pipes, and ground surfaces, and safely draining it back down into the ground. Without soakwells, water can sit on the surface and cause soil erosion, local flooding, muddy water logged soils, foundation damage in buildings, and become a breeding ground for mosquitos. In this guide, we look at the various types of soakwells available, the benefits of installing one, how to do it correctly, and how to look after them.

Types of Soakwells

When choosing your soakwell, you’ll need to consider

  • Your drainage requirements,
  • The type of soil it’s going into,
  • The space available for the soakwell,
  • Your budget,
  • Ongoing maintenance

With that in mind, let’s take a look at the most common types of soakwells available.

Precast Concrete Soakwells

Precast concrete soakwells are a convenient, durable, low-maintenance option particularly suited to drainage systems that must cope with large volumes of water, or need to withstand heavy traffic and machinery. Made from reinforced cement, our precast soakwells are manufactured at Civilmart Kwinana, and delivered direct to our customers’ sites as required.

We manufacture a large range of precast concrete soakwell sizes to fit all types of drainage installations, large and small.

Benefits of Concrete Soakwells

Concrete soakwells have many benefits over other types of drainage systems and even other types of soakwells.

Durable And Long-lasting

Concrete is extremely durable and will easily last half a century or more. That makes concrete soakwells a good option for long-term drainage solutions. Additionally, well-made concrete soakwells will withstand even the most severe weather conditions, and the weight and pressure of heavy vehicles and machinery.


Concrete is low-maintenance, so any product made from it is likewise going to be low-maintenance. It’s also safe and non-toxic, an important consideration given water must pass through soakwells before being recharged back into groundwater supplies. Additionally, concrete is fire-resistant, corrosion-free, and doesn’t degrade over time.


Concrete soakwells are not expensive to install compared to some other drainage systems. They’re also low maintenance as explained above and once installed correctly, can generally be relied on to function well for decades with minimal attention.

Environmental Benefits

They also have considerable environmental benefits. Soakwells are integral in helping to manage stormwater runoff. When water is diverted into them as part of a well-planned drainage system, it reduces soil erosion and allows surface water to drain away properly. The flow-on effects include:

  • Reduced water logging of soils,
  • Less damage to infrastructure foundations,
  • Less stagnant water lying around on the surface,
  • More water being redirected down into groundwater resources

Concrete is also recyclable.

Concrete Soakwell Installation

Although concrete soakwell installation is relatively straightforward, the devil is in the detail as they say. The better your drainage system is planned and the site prepared, the more effective it’s going to be. Here is a brief overview of what you need to consider when installing a soakwell.

The first thing to know is that the amount of water involved, and the size of space you have to work with, will determine your concrete soakwell capacity i.e. what size you need to get. The second thing is that most councils in Australia have installation regulations that govern:

  • how big a soakwell must be relative to the size of the catchment area it will service, and
  • how far from buildings and underground services it must be.

You may also need a permit to install one.

Installation Of A Concrete Soakwell

Install your soakwell in a flat area where it’s going to be most effective in relation to how water flows on the surfaces around it.

Concrete Soakwell Placement

Regardless of council regulations the angle of repose should apply i.e. it should be at least as far away from building footings as the hole into which it’s going is deep. So – 2-metre deep hole must be at least 2 metres from the closest footing.


Clear the site and excavate the hole. In most cases, it should be around 1½ times the size of the soakwell, and deep enough so that the top of the soakwell is between 300 – 500mm below the surface when installed. For safety, always use an excavator appropriate for the size of the soakwell being installed.

Prepare the base of the hole by compacting and flattening the ground so that the tank sits level when installed.

Wrap the tank in Geotextile lining prior to placing it in the ground. This will prevent sand getting into the drainage holes.

Backfill And Compact Around The Soakwell

Backfill around the soakwell with clean sand or gravel in layers. Compact each layer well before adding the next one. This helps stabilize the soakwell.

Once the soakwell is installed, attach any required plumbing and put the lid on before backfilling around the site. Level out the surrounding surface so that water now flows into your newly installed soakwell.

Maintenance & Common Issues With Concrete Soakwells

Strong and durable though they are, concrete soakwells are not totally invincible and do require some maintenance, even if only infrequently.

Overflow in particular is one common issue with soakwells, usually because the drainage holes clog up with leaves and debris, or it receives excessive water flow over and above what it’s designed to cope with. Concrete soakwells can also crack if they’re placed under more weight or pressure than what they’re rated to withstand.

Concrete Soakwell Maintenance

Preventing as much debris as possible from getting into the soakwell in the first place will help stop it clogging up and overflowing. Silt can also be a big issue as it can sit on the bottom of your soakwell and slowly build up a barrier and prevent the water from draining into the soil. This is usually done with high-pressure hoses and special vacuums to clear the drainage holes and remove collected debris from the bottom. Done regularly, this maintenance will keep a concrete soakwell functioning properly for decades.

Likewise, regular inspections can spot damage like cracks before they become major issues. Minor cracks and chips in soakwells can often be repaired with a cement-based mortar mixed and applied as per the manufacturer’s instructions. Another maintenance point is that steel grids in the lids may also rust out over time and need replacing.

Ultimately though, properly installed and well maintained concrete soakwells like those produced here at Civilmart, will remain operational for years to come.

Why Choose Civilmart for Your Concrete Soakwells?

With a long proven history and reputation for manufacturing excellence across a wide range of concrete products, it makes sense that Civilmart is also an expert and industry leader when it comes to concrete soakwells in Western Australia!

Therefore, if you want the very best in reliable, durable, long-lasting drainage solutions for your property, installing a Civilmart concrete soakwell is the way to go. Contact us today and experience the Civilmart difference!