Treat standing water

Can't toss it? Treat it.

Some water sources are permanent — ponds, rain barrels, catch basins — and standing water left untreated is a mosquito nursery. The fix is BTi: a naturally occurring soil bacteria that kills mosquito larvae and nothing else. No harm to people, pets, birds, fish, or pollinators. Used safely for decades.

BTi doesn't kill adult mosquitoes, so it works best alongside trapping. Think of it this way: treating stops the next generation, trapping deals with the ones already out there. [Trap →]

Where to treat in your yard

The obvious ones first: rain barrels, ornamental ponds, birdbaths, fountains, large planters. Drop a dunk in, mark your calendar for 30 days.

Then do a slower walk around your property looking for the spots people most often miss:

  • Corrugated downspouts — probably the biggest one. Clean them first if you can; treat if water still pools

  • Saucers under potted plants — easy to forget, always wet

  • Low spots in the yard that stay wet for days after rain

Mark your calendar when you treat. Dunks last 30 days; Bits need more frequent reapplication. A reminder in your phone takes 10 seconds and means you won't let a treated source lapse back into a nursery mid-summer.

Check your trash cans

This one surprises people. Trash cans are a significant mosquito source — and not just when there's obvious standing water in the bottom. If you see mold, algae, or bees hovering around your bins, that's a sign conditions inside are hospitable to larvae. Rinse them out regularly. If the bottom collects water after rain, toss in a piece of a Dunk or a pinch of Bits.

Shared alley bins and recycling cans are worth a look too — a neighbor's neglected bin can undermine everyone's effort on the block.

Underground Infrastructure — the shared problem

There are a number of underground structures in our streets and sidewalks that collect standing water and are major mosquito breeding grounds.

  • Catch basins: those storm drains where the street meets the curb often collect water before flowing out into the sewer system. This can be by design or the basin is clogged with debris — either way there’s enough standing water to host a huge mosquito party.

  • Underground utility vaults: often covered by manhole covers with small “pick-holes” in them (for when they get pried up). Those little holes allow water into the vault, where it collects in the bottom.

  • Sewer grates: similar to utility vaults, but are covered by open grates vs. manhole covers.

We're working with DC Health to treat all of these common sources systematically across the city. DC Health only treats standing water that has been submitted as a complaint — so we need to make sure those complaints get to them. Also, every submission builds the case for the resources they need citywide.

Here's how it works: If you spot a catch basin or other structure with standing water, either:

We'll share all reports with DC Health every 2-3 days so they can treat whole areas together efficiently rather than scattered individual treatments — and we can problem-solve together if they get overwhelmed. 

The full picture

Treating cuts off the next generation. But mosquitoes already hatched and flying need a different solution. The committee's approach works as a system: Toss what you can, Treat what you can't, and Trap the adults that make it through. The more households doing all three, the less hospitable the entire neighborhood becomes.