If you don't want to risk killing people then don't put landmines in your Wards. You don't have to do that - and if you do then you've left a killing spell where anyone can trigger it. Putting landmines in Wards that anyone can trigger is a bit like putting real landmines on your lawn (to keep intruders out) and blowing up your mailman by mistake - either way you're guilty of murder.
Spoilers for Changes. Which is why when Harry heard that the cops were getting a search warrant he spent "I have to run" time dismantling his wards. This left his apartment undefended and meant that he ran out of "get out of town" time and had to flee to the Nevernever.
But remember - when you put a landmine in a ward it doesn't have to be a "kill" spell.
Richard