Most people planning a demolition focus on the obvious stuff. Asbestos removal, council permits, which contractor to use. But there’s a whole mess of complications underground that nobody really talks about until it becomes a problem.
Every property in Perth has services running underneath – water, sewer, power, gas, telecommunications. When you demolish a house, you can’t just leave these connections flapping in the breeze. They need proper disconnection, and that’s where things get complicated.
What Actually Needs Doing
The disconnection requirements aren’t optional. Each utility has strict rules:
Power needs Western Power to physically disconnect at the street. Not just at your meter – the whole service needs to be made safe so demolition equipment won’t hit live cables.
Water mains need capping by a licensed plumber. Sounds simple, but where exactly do you cap it? At the meter? At the house? What about the pipe running between them? Different situations need different solutions.
Sewer connections are particularly tricky. You can’t just block them off at the house – they need proper disconnection at the junction point, which might be several metres from the building. Stuff this up and you’ll have sewage problems or damage the main sewer line.
Gas requires a licensed gas fitter to disconnect and make safe. Old gas lines can’t just be abandoned in place – they need proper decommissioning or removal.
Then there’s telecommunications. In older areas of Perth, you might have multiple generations of cables – old Telstra copper, newer connections, NBN infrastructure. Each needs consideration.
Why the Plans Are Usually Wrong
Here’s something the industry knows but nobody tells property owners: those nice official plans showing where services run? They’re often completely wrong.
Services get moved during repairs. New connections get added. Old ones get abandoned but left in place. Nobody updates the master plans. So that sewer line marked as running straight to the street? Might dog-leg around a tree that was removed 20 years ago.
This is why experienced demolition contractors don’t just trust the paperwork. They:
- Get Dial Before You Dig reports (legally required anyway)
- Use service locators to trace actual pipe and cable runs
- Do careful hand excavation in suspect areas
- Apply years of local knowledge about common service routes
The Abandoned Service Mess
Perth’s older suburbs are riddled with abandoned services. When copper phone lines got replaced with fibre, the old cables often stayed in the ground. When galvanised water pipes got replaced with poly, nobody dug up the old ones.
During demolition, these create real problems. Is that pipe live or dead? Is this cable carrying power or just old telecommunications? You have to treat everything as live until proven otherwise. That takes time and money, but beats the alternative.
Services That Aren’t Even Yours
Here’s a fun complication – services running through your property that belong to other people. Common scenarios:
Battle-axe blocks where the rear property’s sewer runs through your place. Stormwater from uphill properties draining across your land. Shared service trenches in older subdivisions where multiple properties use the same trench.
You can’t damage these during demolition. They need protection, and your demolition contractor needs to know they’re there. Hit your neighbour’s sewer line and you’re paying for repairs.
How the Big Players Handle It
Major infrastructure contractors deal with this stuff constantly but on a massive scale. Companies like Aqua Pipeline Contracting installing new water mains through built-up areas have to navigate thousands of existing services without hitting any of them.
They use sophisticated detection equipment, detailed procedures, and careful planning. The scale’s different from house demolition, but the challenge is the same – work around what’s already there without breaking it.
What Goes Wrong and What It Costs
Hit a water main during demolition and you’ll know about it immediately. The water corporation charges for repairs, plus water loss. Emergency plumbers don’t come cheap. Your demolition stops while it’s fixed.
Damage a sewer and it might be worse. Sewage backing up into neighbouring properties, emergency repairs, potential health department involvement. The bills add up fast.
Hit power or gas and you’re looking at serious safety issues on top of repair costs. Telecommunications might seem less critical until you realise you’ve knocked out internet for half the street.
Insurance might not cover you if proper precautions weren’t taken. “We didn’t know it was there” isn’t a valid excuse when you didn’t do proper service location.
Getting It Right
Good demolition contractors have systems for managing underground services:
They start with proper investigation – not just relying on plans but actually locating services. They arrange disconnections through licensed trades, with proper permits and inspections. They mark everything clearly so machine operators know where not to dig.
During demolition, they protect services that need to stay. Hand demolition near service zones, barriers around critical infrastructure, constant vigilance. After demolition, they leave clear markers for the builder who comes next.
Questions to Ask Your Demolition Contractor
When getting quotes, ask:
- How do you locate underground services?
- What’s included for service disconnections?
- Who arranges utility company disconnections?
- What happens if you hit an unmarked service?
- How do you document service locations for future reference?
Vague answers or “she’ll be right” attitudes are red flags. Professional contractors have clear processes and can explain exactly how they handle services.
Setting Up for Success
If you’re demolishing to rebuild, think ahead:
Keep useful connection points. That sewer junction might be perfect for your new house. Document everything – photos, measurements, depths. Your builder needs this information.
Consider future needs. Want three-phase power later? NBN to the house? Installing conduits during demolition is easier than trenching through a finished landscape.
Leave physical markers showing where services are. Saves your builder time and money relocating them.
The Reality Check
Underground services complicate every demolition. They’re often not where they should be, disconnection requirements are strict, and mistakes get expensive fast.
But this isn’t some unsolvable problem. Thousands of demolitions happen successfully across Perth every year. The difference between smooth demolition and disaster? Taking underground services seriously from the start.
Don’t let anyone convince you it’s no big deal or something to sort out as you go. The time and money spent properly managing services is nothing compared to the cost of getting it wrong. Get it right, and your demolition runs smoothly. Cut corners, and those hidden services will cause major problems.
