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We recently had some work done on our house and it included painting a room. After the contractors left we discovered, through our security cams, that they had been using our backyard to clean their painting equipment, over a 3 day period. They were mostly using our nomo grass area to washout water soluble paint from brushes, rollers, pans and buckets. They would then spray down the paint until it wasn’t visible from the surface. They also left a lot of paint residue on surrounding plants and trees from flicking the brushes dry. It’s a water soluble latex paint, both matte and gloss. My question is, how bad is this for the lawn and garden?

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  • From my experience having painters I do believe that this is normal practice for painters and is kind of a last remaining option ensuring the paint does not make it into sewers, water ways or landfill, all banned methods of disposal for paint in most locations. Taking waste water with them to a water recycling plant that accepts paint waste would be theoretically ideal but I don't know what facilities exist or how many painters offer this. The only other way is letting it fully dry out and then it can be disposed of but doing so with waste from brush clean up may be difficult
    – tomr
    Feb 1, 2023 at 6:29

3 Answers 3

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A quick search indicates that latex paint can be a nasty pollutant in large quantities, but not in the small quantities you're talking about.

This site has a good discussion of paint contents and their toxicity, if any. It does not discuss contaminated soil, however.

I doubt that the amount of point in your yard is a concern because you say that the painting crew only dumped diluted paint onto the grass and then watered it in, effectively diluting it further. I would be more concerned if they had done this in a vegetable garden.

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    Concur - its not ideal, but better than dropping the wash-water into a sink or drain.
    – Criggie
    Jan 30, 2023 at 3:06
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    @Criggie Is it really? Does even water-based paint clog sewers when diluted, or is there some other problem with washing in the sink?
    – jpa
    Jan 30, 2023 at 7:11
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    the main problem is cleaning the sink afterwards.
    – Jasen
    Jan 30, 2023 at 8:31
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    @Jasen starting with a wet sink, and washing the bristles first under running water, then with soap, then plenty more running water is no problem. The paint stains in my utility room sink are from leaving my daughter's paint to soak - fine with tempera, not with acrylics
    – Chris H
    Jan 30, 2023 at 10:08
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    it's not so bad if the sink is trainless steel. but on plastic even very dilute acrylic paint can leave a mark.
    – Jasen
    Jan 30, 2023 at 11:03
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I did this in my backyard without thinking twice. No issues with plants.

From the theory: Latex paint is actually biodegradable and what is not biodegradable is mostly mineral content.

It is also safe to touch for humans and pets, otherwise we would not use it in the first place.

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  • Titanium dioxide is a carcinogen but is in 70% of latex paints and mercury may be in some exterior paints (see the link in my answer below for a little more info). Titanium dioxide would only be a problem when the paint is wet, I believe, and then at high levels of exposure like those experienced by professional painters. Just because we're allowed to use something doesn't mean it's perfectly safe - especially pesticides.
    – Jurp
    Jan 30, 2023 at 12:39
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    Titanium dioxide is also a very common ingredient in sunscreens. It's one of the two main UV filters that cause sunscreen to have a white cast. The carcinogenic risk is pretty negligible.
    – blues
    Jan 30, 2023 at 12:52
  • @blues - yep, the risk with titanium dioxide is with prolonged exposure, which is what I was trying to say in my comment but probably didn't. Sunscreens may have other problems, but they involve Oxybenzone, which MAY be a reef-killer and/or endocrine disrupter. Or not. The lack of info on some of this stuff is disappointing...
    – Jurp
    Jan 30, 2023 at 14:42
  • Wow. This is real a bad and ignoring behavior.
    – Semo
    Jan 30, 2023 at 14:52
  • @Jurp the biggest risk with TiO₂ is from powder, by inhalation
    – Chris H
    Jan 31, 2023 at 9:29
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This is really annoying and I feel sorry for you. It is very important to know exactly what kind of paint was used. Names and bills can help. From the names of the paints/buckets, you can find the safety data sheets (online, too). They'll explain what hazardous substances maybe mixed inside them - or mixed not into it.

For example, there are water soluble paints, that contain really long-lasting and dangerous anti-fungal substances, that can kill nearby plants. It depends on the amounts of water, color and other substances dumped there. This is all we don't know.

Also part of decision making: Where is the painted building located? Is it in a water protection area? Is it close to a municipal water plant? Can the water with the solution flow into a lake or sewage and sewage treatment plant?

There can be significant fines, if you get caught, when a jealous neighbour sneaks on you.

If you'd just think of the environment, call or sue the company to remove the contaminated soil on their money.

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    Note that safety data sheets tend towards the alarmist side of things: they're intended for people who deal with the materials in bulk quantities on a daily basis, not the small amounts you'd find in an end-of-day paintbrush cleaning.
    – Mark
    Jan 31, 2023 at 2:22
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    The safety data sheet is based on complete emotionless verifiable data and proven knowledge in terms of impact, that chemicals have on living things. I want to focus on the sheet and suggest to take measures better soon than late.
    – Semo
    Jan 31, 2023 at 7:53
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    This is a good point - while the risk is probably low in practice, some paints especially for damp areas have anti-fungal agents added. You may not want such biocides in the garden even dilute, but it's probably too late already
    – Chris H
    Jan 31, 2023 at 9:31
  • @Semo, I suggest you take a look at the following safety data sheets for ethanol, sodium chloride, and water. In particular, note the first-aid measures for spilling ethanol on your skin, the large number of "no information available"s for salt, and the eye/face personal protective gear recommendations for water.
    – Mark
    Jan 31, 2023 at 22:05

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