Very very low chances. But this is more about covering one's ass (avoiding liability altogether) instead of doing proper plumbing work and estimating failure probabilities.
I don't think you will avoid liability in any way by using a plumber, as if you will even remember who it was 10 years later.
You are more likely to puncture a pipe nailing a picture to the wall or putting down carpet.
It's amazing in Germany everybody installs their own kitchens in rental flats, which they move from flat to flat, plus their own washing machines without issues.
I forgot about this until I was recently looking at work in Munich. It seems that built in kitchen are becoming more common at about 40% of flats in the range I was looking at.
Installing a washing machine? As in the no tools required pipe from the wall, the other pipe to the wall and finding a socket somewhere? I'm amazed people pay plumbers to do it!
You are positive it was the dishwasher? Maybe they had a bath every single day and that was the cause?
As I understand it, the aquastop pipes are a pipe in a pipe and only shut the water off if the inner pipe bursts. I've never ever ever seen or heard of an appliance hose breaking, and of course it's not going to detect a leak from a pump that leaks a little unnoticed for days or weeks until some damage is done.
For OP as long as they're sensible it should be completely fine, just don't do what I did and forget to put the drain hose in the sink.
As for the comparison to Germany, if you install or get installed appliances yourself, I'm sure you you yourself would be liable for any damages. If the landlord has fitted an appliance for you then more likely the landlord would be liable for damage from leaks.
In an old house washing machines and such like might not be desired because of noise.
Decent dishwashers actually use less water than a dish wash done manually, so perhaps he should be charged less
Like us they showered each day. We discussed this with them and concluded the dishwasher was the only difference. They washed their dog in the garden with a hose.
They then asked the landlord to install a dishwasher.
Precisely why you take out 3rd party liability insurance.
Or the landlord needs to, which costs money --> they don't want to do it.
I am sure the landlord will have liability insurance, if a tile blows off the roof & land on somebodies car for example. Liability insurance is cheap.
I see I misread your initial post. I thought they had the dishwasher and their water consumption was more.
I still find it hard to believe a dishwasher (for a couple) will cause a 50% difference in water consumption.
All tenants should have a 3rd party liability insurance, and most landlords, including us, insist on seeing it. Sometimes at the tenants request we arrange it for them and they pay the premium. This covers all damage within the flat, such as water damage, fire etc.
The landlord will also have a liability insurance, which will cover him for all damage to the external part of the building, plus any claims made by the tenant if for example, a badly fitted window blows open and hits the tenant.
As for a dishwasher as you describe, no need to ask for permission and just take it with you when you leave.
I don't understand why tenants should be forced to have insurance for an appliance installed and fitted by the landlord. e.g. in case a dishwasher springs a leak and damages the property.
The liability insurance is to cover damage caused by the tenant, for example (among many others) if he leaves taps running and the bath or sink overflows or he manages to set fire to the place. A badly fitted or damaged appliance would be the landlord's responsibility if it was originally installed by the landlord.
If for any reason the tenant took it upon himself to fit an appliance, and it caused damage, then it would be down to the tenant to pay - hence the insurance.
My new dishwasher is backfilling (I need to raise the drainage pipe - the guys I paid for installation only did 30cm - the manual says 50cm). I guess that might cause trouble if left for a few days.
Are you sure it's not a fault with the inlet valve?
Exactly my point. i.e. a reason why a landlord would not install one themselves.
Yes.
He/she means back-filling from the drainage hose. If it's not in some place higher than the water level in the sink then the contents of the sink can drain into the dishwasher - the u-bend isn't high enough. Usually just needs tying up close to the top of the sink.
And that's different to back-flowing down the feed pipes which can happen if there's work in the house and the water supply pipes are drained. Theoretically water that's in the appliance, including contaminated water, could get sucked into the supply pipes and would come out potentially through someone else's kitchen or bathroom tap etc. when things are connected back up. Not really what you want. It's unlikely but obviously does happen hence the requirement in some places/cases to have a non-return valve.
I do agree that the risk of leak/electric problem is low. Anyway, to be on the safe side, make a schema / diagram of the installation, something simple by hand, that anyone can understand, showing that no changes will be made to the facilities. On top some paragraphs in German saying that there will be no change to the infrastructure, second that this is environmental friendly saving water and electricity (although not her problem as you pay for it), this is safe (unlikely water leak/electric problems), and finally that you are responsible for any damage it might cause and will inform her about any issue caused by the dishwasher.
Unless she is lazy to read or interpret a simple diagram, she will have all the data to have an informative decision.
You will make everything clear and transparent, and avoid to have to explain any other issues if she sees the counter-top dishwasher during a visit to your apartment for any other reason. As you said, she is troublesome and will implicate with you if you communicate or not, than better to try to communicate.