Where the wash water goes
Exterior cleaning in Ottawa: the by-law that governs the runoff
Washing a house sends everything it removes somewhere. In Ottawa, the storm sewer at the end of the driveway does not go to treatment, and the Sewer Use By-law is written around that fact.
A storm sewer is not a drain to treatment
Ottawa's Sewer Use By-law prohibits discharging or depositing matter of any type into a storm sewer, a watercourse, or a municipal or private sewer connection to a storm sewer where that matter has any of the characteristics the by-law lists. The City's own advice to residents puts it in plainer words: do not allow chemicals, wash water or hazardous waste to enter the storm sewer.
The by-law also makes the person who discharges responsible for the consequences, including the cost of investigating, repairing, cleaning or replacing any part of the sewage works that is damaged as a result.
That is the question to put to a contractor before they set up. Where is the runoff going, and what is in it. On a paved driveway that slopes to the street, the honest answer is the storm sewer unless something is done about it.
The chemistry question, before the pressure question
Soft washing works by chemistry rather than force, which makes what is in the mix the thing that matters. Health Canada states that it is never safe to mix bleach with other cleaning products, because bleach reacts with anything containing ammonia or an acid, including vinegar.
Ask what is being applied, in what dilution, and what happens to the rinse. A company that can answer those three has thought about the by-law. A company that answers with pressure ratings has answered a different question.
What a homeowner can settle in advance
- Confirm which surfaces are being cleaned and by which method, because siding, brick, a deck and a roof are four different jobs with four different risks.
- Ask how runoff is contained or directed away from a storm drain, and what happens on a driveway that slopes to the street.
- Get the price and scope in writing. Where a written estimate is in the contract, the final price cannot be more than ten per cent above it unless you agree to a change and sign it.
- If you sign in your home, you have ten days from receiving the written copy to cancel for any reason.
Sources, checked 2026-09-18:
Buyer guide
Hiring an exterior cleaner in Ottawa
What separates a great exterior cleaner from a cheap quote, and the questions worth asking before you sign.
Soft washing is not pressure washing
Siding, stucco and roofs are cleaned with low pressure and a cleaning solution; high pressure on those surfaces forces water behind them and strips finishes. Ask which method they will use on each surface, and be wary of anyone who answers 'pressure wash' for everything.
Confirm insurance and working-at-height practice
Window and roof cleaning means ladders, and on a two- or three-storey Ottawa home that is real risk. Ask for proof of liability insurance and WSIB coverage, and how they access upper storeys.
Ask exactly what a window clean includes
Prices vary because the scope does. Confirm whether the quote covers interiors as well as exteriors, and whether screens, tracks and sills are included or billed separately.
Book it around the salt
Spring is the busiest window because road salt, sand and winter film come off then. Booking early in the season usually means better availability, and pairing it with fall eavestrough cleaning often costs less than two separate visits.
April to October
When should you book an exterior cleaner in Ottawa?
Exterior washing needs water that stays liquid on the surface being cleaned and on the ground around it. April is the first month of an Ottawa year to average above freezing across the whole day at 6.2 °C, and November falls back to 2.0 °C with overnight lows below zero.
That leaves roughly April to October, which is why this work disappears from Ottawa in winter rather than merely slowing down.
Temperatures are the Environment and Climate Change Canada: Canadian Climate Normals for station OTTAWA CDA, 1991-2020. Checked 2026-09-10. Any single year can run warmer or colder than the normals.
Before you hire
What should you check before hiring an exterior cleaner in Ottawa?
Wash water and detergent from exterior cleaning can reach a catch basin untreated, which the City of Ottawa addresses through its Sewer Use Program and the guidance it publishes for householders. Ottawa Service Directory is a listings site, not a regulator: we publish what a business reports about itself, so confirm what applies to your job with the source below and with the business before work starts.
Source: City of Ottawa Sewer Use Program: what you do at home matters. Checked 2026-08-24. Rules and thresholds change, so confirm before work starts.