drainagegutters
My downspouts go along the wall down to the garden level. I will install rain grates below it to collect the water and direct it to the street.
I will make something like that.
I think being buried will prevent it from shifting from people walking over it, right?
Do I need to make it above grade to prevent debris from falling into it? I really have no idea about it, as I always seem those grates on floored areas, never on garden.
In the short term, you could waterproof the foundation with some sealant paint like Drylok.
Longer term, you need to fix the problem by directing water away from the house. Is there cracking where the patio meets the house? That would indicate subsidence at that side of the patio, at which point I would definitely call in the professionals.
The next question is how much of a slope there is, and how much you would need to build up the house side of the patio. A thin layer of concrete is easy to apply; you just need to get it thick enough that it won't flow so much that it levels itself out before setting. Getting it looking good is more difficult, but can be done with care, but again you're balancing time to do that versus the concrete setting as you're working with it. If this is someplace that people will use a lot, so you want it to look good, you might still want to pay someone to do it.
Your eavestroughs (or gutters, in some parts of the world) collect the rain from your roof and direct it through a downspout to the ground level. It sounds like you have concrete splash blocks below your downspouts - like this:
(Besides preventing soil erosion, the splash blocks keep the dirt from splashing up on your house.)
Drainage is easy - water goes downhill. Just make sure you have a constant downhill path for the water to flow and you're golden. It won't go uphill into a raised planter, unless you have some special capillary mat or plans with long roots. Plantings are good to slow down the flow of water and also absorb it.
You could put any old soil in to fill in the erosion. If you don't have a splashblock, then you should get some -- flat rocks will work also and are often more aesthetically pleasing.
I agree that rain barrels are unsightly, so don't really like them myself. I once put in a french drain, but that was a lot of work. (Dug a trench, put in geotextile, then some gravel on top of the fabric, then 4" weeping tile, then some more gravel, covered the geotextile over top, then backfilled. The geotextile fabric is to prevent dirt from washing into the gravel and eventually blocking it from working effectively for drainage.)
Best Answer
Connecting the downspout directly to an underground pipe will prevent debris from entering the system. It will probably be easier and cheaper to construct as well.