Can you legally wash a car in a driveway in the GTA?

Read five separate by-laws written by five separate legal departments over twenty years and you expect five different answers. You do not get them. Toronto's Municipal Code § 681-4F(1) prohibits a discharge to a storm sewer with a “visible film, sheen or discolouration”. Mississauga's Storm Sewer Use By-law § 3.2(c) says “a visible film, sheen or discolouration on the water surface”. Peel's says “visible film sheen or discoloration”. York Region's § 5.1(c)(ii) says “a visible film, sheen or discoloration”. Halton's § 5(1)(h)(iii) says “visible film, sheen or discolouration”.

The reason that phrasing keeps recurring is what makes it matter to you: it is a test an enforcement officer can apply standing on the curb. Most of what these by-laws regulate needs a certified lab and a sampling protocol. This clause needs eyes. If the water leaving the car is visibly filmed, sheened or coloured when it reaches the drain, the discharge is already outside the by-law, and nobody has to prove anything about parts per million first.

Soap is what makes it visible. So is the road film, brake dust and oily grime that a maintenance wash exists to remove. Which is why “I'll just rinse it in the driveway and let it run to the curb” is not the safe default a lot of people assume — it is the specific thing the clause describes.

This is a living table, not a finished one. A row exists once we have loaded the by-law on the region's or city's own site and read the clause there. Regional rows cover every municipality inside that region, because in Peel, York, Halton and Durham the sewer-use by-law is a regional one — which is why Vaughan appears here even though Vaughan's own website has refused us every request we have made to it.

Jump to a row: Toronto · Mississauga · Brampton and Caledon (Region of Peel) · Markham, Vaughan, Richmond Hill and the rest of York Region · Oakville, Burlington, Milton and Halton Hills (Halton Region)

Durham Region — Pickering, Ajax, Whitby, Oshawa, Clarington, Uxbridge, Scugog and Brock — is the gap. Durham's own storm sewer page names Sewer Use By-Law No. 55-2013 and links to it, and on 30 August 2026 that link returned 404 to us, as did the document URL behind it. We know the by-law exists and we have not read a word of it, so Durham is not in the table. If you detail in Durham, assume the same visible-film rule applies until the Region tells you otherwise, and ask them: the by-law is listed at durham.ca under regional government and by-laws.

Every row above is also published as machine-readable JSON and CSV, free to reuse with attribution to washdash.ca.

Four of the five by-laws cap total suspended solids reaching a storm drain at 15 milligrams per litre, and cap total phosphorus at 0.4 mg/L. Those are the same numbers in Toronto, Mississauga, Peel and York, which tells you they came from the same provincial guidance rather than from five independent judgements about cars.

For context on how tight that is, look at what Halton allows into a sanitary sewer instead: 350 mg/L of suspended solids and 10 mg/L of phosphorus. The sanitary system runs to a treatment plant, so it is allowed to receive roughly twenty times the solids. A storm drain generally runs to a creek or the lake with no treatment at all, which is the entire reason for the difference.

The practical read is not that you should be measuring milligrams. It is that the storm-drain limits were written for water that is essentially clean, and the visible-film clause exists precisely so that nobody has to run a lab test to establish that grey water off a dirty car is not that.

Rinseless and waterless washing is the honest answer for most maintenance work, and it is the reason the technique exists. Two buckets and a few litres, no hose, no runoff heading anywhere. It will not do a genuinely filthy vehicle after a March thaw, but it does the bulk of a regular customer's calendar.

A water-reclamation mat is the answer when you do need volume. The car sits on the mat, the mat captures the runoff, and you take the captured water away rather than letting it find a drain. That is the setup a detailer buys when exterior work becomes the business rather than an add-on, and it is what makes commercial fleet and dealership work possible.

Interior work has no runoff question whatsoever. Extraction, steam, pet hair, salt and odour all stay inside the vehicle, which is a large part of why so many mobile detailers in this region start there. It is also the work that holds up through an Ontario winter, when outdoor exterior detailing is closed for months anyway.

What none of these by-laws do is give you a residential exemption to hide behind. Mississauga's is the clearest demonstration: its exceptions section names residential pool water specifically and attaches five conditions to it, including a slow controlled discharge to the curb and a seven-day wait after the last chlorine dose. A by-law that thought that carefully about a homeowner emptying a pool and wrote nothing at all about washing a car did not forget.

Water is one rule. A business licence is another, and they are not connected. In Toronto the relevant category is a public garage licence, and Chapter 545 defines a public garage to include “a building or place used as a motor vehicle repair shop or for washing or cleaning motor vehicles”. The classifications in § 545-263 split that into a place used for washing vehicles by mechanical means, and “a building or buildings” used for washing them by other than mechanical means — and § 545-270 defines a manual car wash as “a facility for washing vehicles by means of a hand-held device”.

Every one of those definitions is anchored to a building, a place or a facility. A detailer who arrives at a customer's driveway with a van has none of the three, which is a reasonable argument that the category was written around fixed premises and does not reach mobile work. We are not going to turn that into advice, because “place” is not defined in the chapter and a driveway is arguably a place. It is a question for Municipal Licensing and Standards, and it is worth asking in writing before you scale.

Oakville is the one municipality where the answer is about to change, and it has a date. Business Licensing By-law 2026-012 takes effect on 4 January 2027, and the Town's own announcement of it says the new by-law adds a licence class for “mobile motor vehicle service (such as at-home/on-site repair and maintenance)”. At-home, on-site vehicle work is exactly what mobile detailing is. Whether cleaning counts as “repair and maintenance” is not something we could read in what the Town has published so far — so if you detail in Oakville, email licensing now and get the answer in writing while it is still cheap to get. The by-law it replaces, 2015-075, has no such class.

Start with the region, not the city. In Peel, York, Halton and Durham the sewer-use by-law is regional, so searching “Vaughan car wash bylaw” sends you round in circles when the document you want is York Region's. Toronto and Mississauga are the exceptions in this table: Toronto because it is a single-tier city, and Mississauga because it layers its own storm sewer by-law on top of Peel's.

Search the region's site for “sewer use by-law” and open the by-law itself rather than the summary page. Then go straight to the storm sewer section — it is usually a separate part from the sanitary one, and it is always the stricter of the two. The clause you are looking for is the list of characteristics: film, sheen, layers, pH, temperature. That is the paragraph that decides whether your setup is legal.

Then ask the one question the by-law will not answer: what the municipality expects of a mobile operator specifically. Phrase it as “what is required to operate a mobile car detailing service in your municipality, and how should wash water be managed?”, and write down the date and who you spoke to. If a property manager or a fleet client ever asks, that note is what you will want.

It is not legal advice, and reading a by-law is not the same as getting a ruling on your specific setup. We have quoted the clauses and linked the documents so you can check our reading against the same source we used; where we were unsure what a clause covers — Toronto's licensing definitions, Oakville's new class — we have said we were unsure rather than resolving it for you.

It is also not complete. Five by-laws are in the table and Durham's is not, because its own link to it returned 404 on the day we checked. Municipal by-laws are amended without anyone announcing it to the internet, which is why every row carries the date we read it: if that date is old, trust the link and not us. The whole table is published as JSON and CSV as well, free to reuse with attribution, so anyone can check the reading or extend it.