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Septic tanks vs. sewers: our plumbers in Doncaster explain the difference!

2019-06-17T23:58:11+00:00 June 7th, 2019|Plumbing|

Australia is an advanced, first-world economy. We’re one of the world’s wealthiest countries, with solid infrastructure and a high standard of living.

So it may surprise you to find out that up until very recently (2017, to be specific) many homes in north-east Melbourne didn’t have sewer access!

Yep, you heard that right!

It wasn’t until very recently that all homes in neighbouring Warrandyte had access to a sewer.

We saw this first-hand – our Doncaster plumbers received many a call to connect homes to the newly-built Warrandyte sewer.

Until then, many homes relied on old-fashioned septic tanks for their domestic wastewater needs.

What exactly is a septic tank?

Just like switchboard operators, septic tanks are (supposedly) a relic of a long-bygone era.

So much so, that many younger readers might not even know what they do, or how they work!

Before we have sewage, we had septic tanks. Essentially, these are concrete chambers located underground to store all the waste a typical house generates.

Some people operate under the belief that septic tanks are essentially giant storage tanks.

This is completely wrong – septic tanks are actually a lot more complex than many give them credit for, using natural techniques to filter and dispose of wastewater.

Generally, the idea behind septic tanks is as follows:

  1. The idea is that the tank ingests waste
  2. Anaerobic bacteria breaks down the waste water – over time, solids settle down at the bottom to form sludge, while oil and grease float to the top as scum
  3. The remaining liquid wastewater (effluent) is piped out to the drainfield area (otherwise known as the leach field)
  4. These outlet pipes contain tiny holes, which allow water to start seeping out into the soil in the drainfield area
  5. Bacteria in the soil and gravel further decompose the waste in the effluent – the remaining water then seeps down into the groundwater

Still confused? Here’s a handy video explaining the basics.

How do sewers work?

If you live in Melbourne, chances are your home uses a sewer.

It’s an essential part of daily life – but how much thought do you actually give your home sewage system?

We’ll bet the answer is “not a lot!”

Essentially, all the drains in your house meet at the sewer connection pipe.

This pipe connects all the water-using fixtures in your home to the sewer system, where it’s then transported to a plant for treatment.

Using a variety of systems, the treatment plant takes the waste out of your wastewater.

What’s the difference? Is one better than the other?

As anybody whose house features a septic tank no doubt understands, there’s no day-to-day difference between houses with septic tanks, and those with sewer connections.

Periodically, owners of septic tanks may need to have theirs pumped, and sludge removed.

Other than that, there’s little change to your day-to-day routine – wastewater goes down, and you never have to worry about it again.

That said, there are a couple of fundamental differences between the two…

The breakdown process

If we’re talking about differences, we may as well start with the biggest one!

As we mentioned above, septic tanks use self-forming bacteria to break down wastewater.

This separates the water content from solids, which either float to the top or sink to the bottom, leaving (relatively) clear water.

By contrast, sewer systems use mechanical processes to break down water.

Many wastewater treatment facilities use a system of filters, tanks and pumps to take the waste out of wastewater.

This accelerates the natural processes you find working in a septic tank – the resulting effluent is then disinfected, usually with chlorine.


Many laud septic tanks as the more flexible option, citing the fact that septic tanks can be built anywhere with suitable soil or gravel for effluent to leech into, without the need for expensive sewage systems to be installed.

This is true – however, the issue with this is that properties that don’t have a suitable drain field are out of luck!

  • Your home is built on hard, non-porous clay or rock
  • Nearby soil may not have the natural bacteria needed to decompose waste
  • You may simply be too far from the nearest suitable patch of soil
  • The water table could be too deep for effluent to drain

What happens when things go wrong

One of the big advantages of septic tanks is that they operate independently of other houses in your neighbourhood – a problem with one person’s tank doesn’t affect your wastewater.

By contrast, sewers are communal – each house in your neighbourhood is connected to the same sewer.

Should something go wrong with the sewer system, it won’t just be your home that’s left without proper wastewater disposal – you might just be one of many houses in north-east Melbourne that’s afflicted!


You don’t often think about what goes down your drains.

Many take an “out of sight, out of mind” approach (we don’t blame you!) – with the notable exception of problems like blocked drains, of course.

With septic tanks however, you won’t always have this luxury.

As mentioned above, septic tanks use natural processes to break down and separate solids from wastewater, which then either float to the top or sink to the bottom.

Over time, this creates a thick sludge, which will need to be pumped out.

As anyone who already owns a septic tank knows, this process leaves you unable to use your plumbing fixtures.

What’s more, it also happens on your dollar – while sewer maintenance is the responsibility of your water company, your septic tank is yours and yours alone.

Therefore, any maintenance (pumping and emptying included) is solely your responsibility!

So, what’s the best choice for your home?

The truth is, it depends.

While most of us rely on sewer systems, there are many of us who might prefer a septic tank for one of the reasons listed above.

However, there are also many homes that simply didn’t have the choice!

In particular, many households in Warrandyte continue to rely on septic tanks not by choice, but simply because there’s no sewer system in the area.

Luckily, the North Warrandyte Community Sewer Project gives homeowners in north-east Melbourne the option.

Of course, you’ll still need to be connected!

Plumbers in Doncaster

H2-Pro’s Doncaster plumbers can help!

If you live in Warrandyte and haven’t had an opportunity to connect to the shiny new sewer system, H2-Pro can help.

Our Doncaster plumbers specialise in all manner of domestic plumbing jobs – and that includes sewer connections.

Unlike other plumbers, we’re strictly local – we only work in north-east Melbourne.

You might think of that as a weakness, but really, it’s one of our greatest strengths.

That’s because the north-east has unique plumbing requirements.

For example, homes here tend to skew on the older side of things.

Not to mention, most other areas of Melbourne already have sewer coverage, so few other plumbers even know how to perform sewer connections anymore, as there hasn’t been any demand.

Since our Doncaster plumbers work solely in the north-east, we’re intimately familiar with these unique issues.

Combine that with our trademark customer service, punctuality, cleanliness and a lifetime 10% discount for locals, and it’s clear that we’re the team to call for your sewer installation!

Give our team of local plumbers a call today on (03) 9844 1444, or click here to get in touch.

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