Hello. I am a solicitor with over 15 years experience. I will try to help you with this.
If the puddle is caused by water discharging from your land then you may be liable, however if the true cause is rain penetrating their elderly garage then you are not responsible at all. They would need to be able to prove that it was more likely than not that the cause of the puddling is water flowing from your garden. Will they be able to prove this?
The water I think is falling as rain between the two garages and as there is 2 foot lower than ours the water takes the downward route and goes into there garage.
OK whose land lies between the garages? He will also need to take adequate steps to keep his garage in good repair and if water is flowing through a hole caused by his own neglect then he will not be bale to claim against you successfully.
We have 2 rain barrela on the back of our garage which fill from our garage guttering, then when they overfill there are 2 pipes attached which take the excess water down to the bottom of the drive, a long way from the garage. We then have the downpipe that after the barrels full any excess goes into a funnel and into another pipe down the side of the garage onto the drive. The neighbour says the problem is the 10 inch gap beteen theis downpie and the funnel that is the problem, as when the rain is really heavy like last weekend, the funnel cannot take the excess flow. But here garage gutters are full of water and are not draining away and so when there is excess rain her gutters oberflow too. How can she say that the water in the puddle is ours and not hers from her overflowing guttering?
We have had the worked checked yesterday by a roofer who says there is nothing more he can do and that everything has been done that can be done.
It sounds like your neighbour would have trouble proving it was your fault.
The land between the 2 garages is half ours & half theirs and slopes down towards their garage.