How to Install a Soakwell Like A Pro: What You NEED To Know

For those DIY-minded folk, I thought I would put together a guide for installing your own soakwell.  I first look at the tools and materials you need, followed by the steps to take.  I hope you find it useful:)

Digging a hole for a soakwell

#1: Decide on how many soakwells you need

First, you need to determine how many soakwells you need.  This can be done by working out your catchment area (this is your roof area) combined with the predicted rainfall for the area you live within (your local council will have this in).

To help out I’ve included some links to online calculators that can assist with this:

If working out via a calculator isn’t your preference then as a rule of thumb, if you have a house with no adjoining walls to our neighbours, then you can look at installing one standard soakwell per downpipe.

Decide on the type of soakwell to install

There are a number of different soakwells to choose from, however, if you’re doing DIY then I recommend going with the polypropylene cube type soakwells as these are the easiest and in my opinion the most effective soakwell out of the different types available.

Reasons why I prefer polypropylene soakwells can be seen here.

See also: What is the best soakwell to use in WA?

#2: Buy the soakwells and materials needed

Before you get started you’ll need to ensure you have the soakwell and appropriate materials and the soakwell(s) you need.  Here’s a checklist you can use:

Soakwells Materials

  • The soakwell(s) either:
  • Stormwater grate(s) for the base of your downpipes;
  • 90mm PVC drainage pipe to run from the grates to the soakwells (usually comes in 6m lengths);
  • 90mm PVC connections and fittings;
  • Duct tape for attaching protective fabric; and
  • PVC pipe glue (PVC solvent cement).

See also: Where to buy soakwells in Perth, Western Australia?

#3: Grab the tools out of the shed

Once you’ve purchased your soakwells, the next thing you’ll need are the tools to get the job done.  To help I’ve provided a checklist of tools I use when installing soakwells:

  • Hacksaw for cutting the PVC pipe;
  • A shovel (Ideally a plumbers shovels as they are suited for digging holes);
  • Trenching shovel (for digging out trenches for your drainage pipes);
  • A pick or a mattock (for breaking up any stone you may come across when digging the soakwell hole of trenches for your pipework);
  • A spirit level;
  • Pack of small wooden stakes (If you installing a few around the property and want to mark them out);
  • A tape measure;
  • A pair of gloves; and
  • Hand compactor (Sometimes known as a Tamper.  To be used to compact the base of the hole before dropping in the soakwell).

#4: Choose your Soakwell Location

Once you’re ready to go the next step is to carefully identify a suitable location for your soakwell(s).  Note when choosing a location you must ensure that the soakwells are at least 1.5 – 1.8m away from the foundation of your property and the appropriate distance from your boundaries.  

For more information on the regulations and guidelines within your area, check out of local council requirements page with links to the soakwell information for each council area in WA.

See also: Council guidelines for soakwell installation

#5: Assemble the soakwell

If you’re using polypropylene or PVC soakwells, then once you have identified the soakwell location(s) your best to assemble the soakwell(s) and place them next to where you plan to dig the hole for the soakwell(s).  Having the soakwell assembled and positioned next to the hole allows you to gauge how big your soakwell hole needs to be.

#6: Start digging!

Once you’re happy with your soakwell locations you can then start to dig the holes and drainage pipe trenches for each soakwell, however, before you do this you must contact Dial Before You Dig to know where your underground services are.

Why?  This is important else you could put your shovel or pick straight into a sewer pipe, gas line, power, water, phone, or internet fiber cable.

Digging the hole for the soakwell

When digging the hole for your soakwell you want to ensure it’s 300 – 500mm below the ground surface, ideally 500mm if you can.  Once the hole is dug I always like to smooth out and compact the base of the hole to ensure that when it’s dropped in, the soakwell sits on a level surface.

Also, you want to make sure that there are no sharp items such as rocks or tree roots that are likely to protrude into, or pierce the protective fabric around the soakwell.  To prevent this, I usually dig a hole that is at least 20% wider than what the soakwell is.

Useful Tip

If you’re installing the soakwell in a lawn or patio area then I always like to place a tarp next to the hole, putting the soil I dig out onto the tarp. This makes the backfilling and tidy-up process so much easier. When you get to the end of backfilling the soil, you can simply lift the tarp and direct the remaining soil back into the hole leaving a nice clean area around the soakwell.

Digging the trenches for the drainage pipes

Next, you want to dig the trench from the downpipe to the soakwell.  To do this, if it’s a direct run (e.g. no elbows or t-junctions) grab a piece of 90mm PVC pipe and lay it from the soakwell hole to the downpipe.  Mark the sand, grab your trenching shovel, and start digging a trench for the pipe to lay in.  

When it comes to the depth of the trench you want to ensure there is a runoff from where the stormwater grate will sit under the downpipe back toward the soakwell.

Usually, I like to ensure the pipe is a minimum of 150mm under the surface and then increase the depth towards the soakwell hole from there by where I am for a fall of at least 100mm for every 10m.

#7: Wrap up the soakwell in protective fabric

Although not a necessity with concrete soakwells (though still recommended), for polypropylene soakwells or PVC soakwells you’ll need to wrap these in a protective fabric.

Why? This allows rainwater from within the soakwell to infiltrate out into the surrounding sand and soil whilst preventing dirt from entering the soakwell.

Therefore, before dropping your soakwell into the whole it’s best that you wrap it with the protective fabric that came with the soakwell.  To fix the fabric I usually use duct tape.

#8: Install your soakwell

Now it’s time to lower the soakwell into the hole you’ve dug.  If you have a polypropylene soakwell or a PVC soakwell then simply grab the soakwell and drop it in by hand.  Alternatively, if you’re installing concrete soakwells you’ll need to drop them in with the likes of an excavator.

Note, regardless of the type of soakwell you’re installing, be sure to ensure the entry for the drainage pipe lines up with the drainage pipe trench you dug previously.

#9: Install stormwater drains and connect PVC piping

Now the soakwell is in place it’s a matter of installing the stormwater drains and connecting the 90mm pipe to the soakwell. Once the drains and pipe are installed it’s a matter of inserting the drainage pipe into the top or into the side of the soakwell.  

If you’re using a polypropylene soakwell then you’ll need to cut a hole in the top of the soakwell that the pipe will slide into.  To cut through the protective fabric you can simply cut an X shape in the material which cate be opened outwards and later taped to the 90mm pipe with duct tape.

When cutting a hole in the top of a polypropylene soakwell, ensure you’re not cutting into a divider or internal support within the soakwell.  There are a number of different tools you can use to cut a hole for the pipe, though for those that have one, I’ve found a jigsaw works well.

Note, if you know where the pipe is going to enter the soakwell you can always cut the whole prior to dropping the soakwell in the hole.

If you have installed a concrete or PVC soakwell then PVC pipe will be able to slide through the pre-existing holes in the side of the soakwell.

Useful Tip

Always make sure you glue your PVC bends and connections leading down towards the soakwells to ensure they don’t separate over time.

#10: Cover the area and finish up

You’re nearly finished! Now Once the soakwell is installed it’s a matter of backfilling all the soil in and around the soakwell and back into the trenches.

Once you’ve backfilled the soil it’s a great idea to thoroughly soak the soil directly above and around the soakwell.  This will cause the soil to naturally sink and compact itself avoiding any future sinkholes appearing.

After this I then like to manually compact the soil with a hand compactor price to relaying any papers or lawn, that’s if there are any.

Hope this was of help! Thanks for reading:)

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