How to get rid of rats

Step 0 — confirm it is rats

Raisin-sized, blunt-ended droppings and a noise with weight behind it means rats. Rice-grain droppings pointed at both ends means mice, and the whole method is different. Mice vs rats takes a minute.

Step 1 — find the runs before you buy anything

Rats are creatures of habit that travel the same routes nightly, hugging structure. They leave better evidence than mice:

• Rub marks — a dark greasy smear along a wall, a joist, or a fence board at rat-shoulder height. This is the single most useful sign and it is unmistakable once you have seen one.
• Droppings concentrated on the run, rather than scattered widely.
• Runs in vegetation — a worn path through long grass or under ivy.
• Burrows — 50-100 mm openings at the base of a wall, under decking, beside a shed, often with fresh soil fanned out.
• Gnawing — coarse, about 4 mm wide, on plastic pipe, soft mortar, cable, or the corner of a door.

Map it before you buy. Every trap goes on a run you have identified, not where you last saw a rat.

Step 2 — pre-bait for three to five nights

This is the step that decides the outcome, and it is the one everybody skips.

Put your traps out baited and unset. Let the rats feed off them, repeatedly, with nothing happening. Neophobia fades once the object has been part of the environment for a few days and has demonstrably not hurt anything.

Refresh the bait each evening. If the bait is still untouched after three nights, the trap is in the wrong place — move it to the rub marks.

Step 3 — set everything on the same night

On night four or five, set every trap at once.

Simultaneous setting matters because one trap firing is a lesson. If you set one trap, catch one rat, and leave the rest unset, the survivors associate the event with the object and the rest of your campaign gets much harder. Setting six at once takes out a meaningful share of the group before they can learn.

Six is a baseline for an established indoor problem. A yard with continuous pressure needs more, and stations rather than bare traps — see outdoor rat traps.

Step 4 — the first week

• Nights 1-2 after setting: most of the catches.
• Nights 3-7: a tail, usually concentrated at one or two specific traps, which tells you where the remaining route is.
• Any rat that survives a trap will not approach that trap again — see trap-shy rats for what to do next, because setting more of the same will not work.

Reset and re-bait each morning. Wear gloves. Keep the traps where they are as long as they are producing.

Stop when you have five consecutive nights with no catches on baited, armed traps that are still on the runs.

Step 5 — exclusion, which is the permanent part

A rat gets through a gap of about 20 mm and can enlarge a smaller one by gnawing. Walk the building and close:

• Pipe, cable and duct penetrations at the foundation line
• Damaged crawl space vents and air bricks
• Gaps under siding and at the eaves — roof rats climb well and come in high
• The gap around the garage door, and any perished thresholds
• Broken drain covers and disused drain runs, which are a classic urban route
• Gaps where a deck, porch or extension meets the main wall

Use hardware cloth, tightly packed steel wool with sealant over it, or mortar. Rats chew through expanding foam, soft plastic and thin timber.

Roof rats in particular get in high: overhanging branches within about two meters of the roof are a bridge, and cutting them back is often the single most effective exclusion step.

Step 6 — remove the food and the harborage

Trapping into a food supply is a permanent commitment.

Food:

• Trash in hard-sided cans with lids that actually latch
• No fallen fruit left on the ground
• Bird feeders with catch trays, or paused entirely for a few weeks
• Compost in a rodent-resistant bin, no cooked food or meat
• Pet food and water bowls in overnight
• Chicken feed in metal bins; feeders lifted at night

Harborage:

• Log and lumber piles off the ground and away from walls
• Dense ivy and ground cover cut back from the base of the building
• Junk, pallets and tarps cleared, particularly against walls
• Gaps under sheds and decking blocked with hardware cloth

Rats in the yard covers this in more detail, and it is where most suburban rat problems actually originate.

Cleaning up

Rat droppings and nesting material in an enclosed space are the situation where the public health guidance matters. Ventilate first, wear gloves, do not sweep or vacuum dry, dampen with disinfectant, leave five minutes, lift with paper towel, bag it, wash your hands. The CDC guidance linked below is specific.

When to call a professional

• A colony inside walls or under a slab where you cannot reach the runs.
• A large volume of droppings in an unventilated attic or crawl space — that is a respiratory-protection job first.
• A problem that returns within weeks of every treatment, which means an entry you have not found. A survey is worth more than more traps.
• Any infestation in a household with someone immunocompromised.
• A burrow system under a structure, which usually needs proper assessment rather than a weekend.

Saying so is part of the point of this site: it exists to help you do it yourself, which is exactly why it should be clear about where that stops.