Super8man wrote:it floods plus water runs from next door, but only after heavy rain.
My problem when we fill the water will not go anywhere upstream. All Tik says not my problem, up to them.
If I understand correct, water from your "upstream" neighbor will be a problem, as it passes your land to drain away, so better make sure it can pass.
When the water has to soak away, it would mean that you would get very wet, soggy land as well, so your garden will suffer.
Having water standing against your boundary wall will also cause erosion.
Cost of building a deep foundation for the wall to avoid collapse due to wet and weak underground will also be much higher.
One way to do that is to put a drain or ditch at the front, between the road and your property wall.
This will ensure you have better control of erosion and not get problems with your wall and land because of water being blocked from draining away.
I would discuss with the neighbor if possible. Likely he's never thought about it because the land you want to build was vacant anyway.
If he cooperates, you might be able to find a proper and lasting solution, where both benefit and it always helps to have a good neighbor.
Cheers,
Luc