The case for
Water damage causes more loss in vacant properties than anything else, and severity is driven by duration. A supply line that fails with the water on runs at full pressure until someone closes a valve — several hundred litres an hour, for as long as it takes anyone to arrive. The same failure with the supply closed produces essentially nothing.
Shutting off does not stop pipes from freezing. What it does is remove the continuous flow that turns a split pipe into a destroyed building.
Shutting off is not the same as draining
Closing the main leaves water sitting in the lines. That water can still freeze and split a pipe, and when it thaws it releases whatever volume was in the system — much less than a live supply, but not nothing.
Draining is the more complete version: close the main, then open fixtures from the highest point of the house downward, letting air in and water out. Flush toilets to empty tanks. Open exterior faucets after closing their interior shut-offs.
If you drain fully, add a small amount of plumbing antifreeze or mineral oil to traps, since drained traps lose their seal against sewer gas.
When not to
- If the property has a fire sprinkler system, the supply must remain charged. Do not shut it off.
- If the property has a boiler or in-floor heating, the heating loop is separate from the domestic supply and needs different handling. Get advice before shutting anything down.
- If the shut-off valve is old, seized or weeping, do not force it. A valve that fails while you are forcing it creates the exact problem you were preventing. Have a plumber deal with it first.
- If your policy requires maintained heat instead, follow the policy.
- If the property has a humidifier, water treatment equipment or other connected systems, those need to be addressed rather than left pressurised behind a closed main.
The middle option
For shorter absences, or where full draining is impractical, closing supply valves to the highest-risk appliances gets a meaningful share of the benefit for very little effort. Washing machine hoses, dishwasher supply lines and refrigerator ice-maker lines account for a large proportion of vacant-property water losses, and every one of them has its own shut-off.
It is a five-minute job and it removes the three most common failure points without touching the main.
Related questions
Should I shut the water off when I travel?
For an extended absence in an Alberta winter, shutting off the water is the single most effective step available to you. It removes the mechanism for the most expensive thing that happens to vacant homes.
The reasoning is simple. A supply line that fails while the water is on runs continuously at full pressure until someone closes a valve. The same failure with the water off produces nothing. Shutting off does not prevent pipes from freezing, but it dramatically limits what happens when one does.
For it to work properly, shutting off is not enough on its own — the system should also be drained. Open the lowest fixtures to relieve pressure and let standing water out. Water left in the lines can still freeze and split a pipe; you simply avoid the continuous flow afterwards.
Some caveats. If your property has a fire sprinkler system, do not shut off the supply — that system needs to remain charged. If the property has a boiler or in-floor heating, the heating loop is separate from the domestic supply and needs different handling. If the shut-off valve is old, seized or leaking, force it and you may create the problem you were preventing; have a plumber deal with it first.
Also check your policy. Some insurers require water to be shut off and drained during extended absences in the heating season, and some accept maintained heat as an alternative. Which one applies to you is worth knowing before you decide.
How do I drain the pipes before leaving?
The basic sequence is: close the main shut-off valve, then open fixtures from the highest point in the house downward, letting air in and water out. Open both hot and cold at each fixture. Flush toilets to empty the tanks. Open exterior faucets after closing their interior shut-offs.
A few additions that matter. Drain the washing machine supply lines by closing their valves and disconnecting or running a short cycle. If you are leaving the hot water tank drained, follow the manufacturer's procedure and switch off its power or gas first — an electric element energised in an empty tank fails immediately.
Add a small amount of plumbing antifreeze or mineral oil to traps if you are draining fully, since drained traps lose their seal against sewer gas.
Where this gets beyond a homeowner task: properties with boilers, in-floor heating, water treatment equipment, sprinkler systems or complex mechanical arrangements need a plumber. So does any property where the shut-off valve is old or does not close fully.
For clarity on our side — VacantHomes attendants confirm and document the state of your water and operate an accessible main shut-off per your instructions. Draining systems, servicing valves and any work on a water heater is plumbing work and goes to a licensed plumber.
Can I turn the heat off completely?
Only if the water supply has been shut off and the system properly drained, and even then it is a bigger step than most owners realise.
With water fully drained there is no plumbing left to freeze, so the freeze argument for heating disappears. But an unheated building through an Alberta winter has other consequences: condensation and moisture cycling in the structure, stress on finishes, adhesives and materials from repeated freeze-thaw, and potential problems with anything left in the property.
A property with a boiler or in-floor heating cannot simply be shut down — those systems have their own fluid that needs handling, and shutting down without proper procedure risks damage to the system itself.
Your insurer likely has a view on this. Many policies require either maintained heat or a drained system during heating-season absences, and some are specific about which. Confirm before deciding.
For most owners leaving for a season, maintaining a minimum temperature is the simpler and safer choice. Full shutdown makes sense for genuinely long-term vacancy — an estate property with an uncertain timeline, or a property awaiting redevelopment — and is worth setting up properly with a plumber rather than improvising.