Wet and Forget Reviews

If you’re dealing with moss, mold, or mildew stains on outdoor surfaces — decks, driveways, patios, siding — Wet & Forget is one of the more popular options for tackling it without scrubbing or pressure washing.

What it actually does

Wet & Forget’s active ingredient is alkyl dimethyl benzyl ammonium chloride — a quaternary ammonium compound, not bleach and not an acid. It penetrates moss, mold, mildew, and algae growth, and rain gradually washes the dead growth away over the following weeks, so there’s genuinely no scrubbing or rinsing required after application.

It’s registered with the EPA (registration number 84115-1) as a pesticide product for this specific use, which means it’s been evaluated for the uses and application methods on its label — that’s different from a blanket “safe for anything” endorsement, so it’s still worth following the label directions carefully.

Where to use it

Works on a wide range of surfaces: pavements, roofs, painted surfaces, decking, siding, concrete, brick, aluminum, fiberglass, vinyl, teak, PVC, steel, asphalt, and ceramic.

Good for walkways, driveways, roofs, fences, outdoor furniture, playsets, pool liners, and similar outdoor structures. Larger commercial applications (schools, parks, hotels) use it too, since it scales well across bigger surfaces.

How to apply it

Avoid applying on very hot days — heat can evaporate the solution before it has time to work. Aim for a day above freezing, with no rain expected for several hours after application, since rain too soon can wash it off before it’s had time to penetrate.

Moss stains typically clear within a couple of weeks to a month; darker mold and mildew stains can take longer, sometimes a few months, depending on how established the growth is.

For lichen specifically — a combination of fungus and algae — let the solution sit about 15 minutes to soften the outer layer before it can fully penetrate and start working.

Safety — read this before you apply it

This is not a mild, casual-use product, despite marketing language suggesting otherwise. The concentrate’s own safety data sheet lists it as capable of causing serious skin burns and eye damage, and it’s classified as harmful if swallowed. When applying it:

• Wear gloves, eye protection, and avoid breathing the spray mist
• Don’t apply on windy days — overspray drifting onto skin or into eyes is a real risk given the corrosivity
• Keep people and pets off treated surfaces for 4–6 hours, or until fully dry
• If a pet does walk on a wet, treated surface, rinse their paws before they have a chance to lick them
• The outdoor formula isn’t meant for indoor use — ventilation matters, and using it indoors without proper respiratory protection isn’t advisable
• Cover or pre-wet nearby plants before applying, since overspray can cause temporary browning (plants typically recover, but it’s avoidable with a bit of prep)

None of this means the product is dangerous when used correctly — it’s a legitimate, EPA-registered product that a lot of people use safely every year. But “safe” here means “safe when you follow the label directions and basic precautions,” not “harmless to touch or breathe.”

Pros and cons

Pros: long shelf life, biodegradable once diluted and applied, works on a wide range of outdoor materials, one-step application with no scrubbing or rinsing required, effectively removes moss, mold, mildew, and algae.

Cons: may need a second application for heavier or more established staining; the concentrate itself requires real care and protective equipment during handling and application, more than the marketing suggests.

Bottom line

Wet & Forget is a genuinely effective, low-effort way to clear moss, mold, and algae stains from outdoor surfaces without scrubbing or pressure washing. Just treat it with the same respect you’d give any EPA-registered pesticide product — gloves, eye protection, keep pets and people clear until it’s dry — rather than assuming “biodegradable” means “harmless to handle.”