It's possible to craft a sewer grate to drain but I found it's functionality pointless. In my brother's and my 2 horse town on a rainy planet, we have constant flooding issues and have learned to build our city, farms and even own homes with drainage systems (one even sustaining his pet shark). When I found the drain tile I was excited as we've been using different platforms for this purpose, followed by tunnels (aesthetically) or just holes in the background (random platform leading to nothingness=not aesthetic). But it turns out these drains are pointless as 1) the are not walkable platforms and 2) they occupy the LOWER half a single tile. Meaning if I want to use the drains for their only purpose, I have to use them for only aesthetic purposes, by placing them one tile below already existing platforms serving their purpose, making them not aesthetic whatsoever, but confusing and jumbled. Basically pointless. If these drains occupied the TOP half of a tile and functioned as a platform they would not only be useful but also pleasing. Or even if they occupied a WHOLE tile, so that there could be a hole in the background hidden by the drain, eliminating the need for tunnels, but I would choose the former. Thank you.
I think that there are some problems with the way you made your city. Are there any backgrounds exposed to the rain in front of wooden doors? Do you have anything that covers the ground from rain? If you have build your city/base/town right, you shouldn't have to build a drainage system.Maybe other types of doors will solve your flooding issues? Why do you need drains that act like platforms anyway? You could just place some at the bottom and they will suck out all of the water. The current drains should not be changed as this will ruin the looks of the current airlocks, but other types of drains could be added, especially a drain that acts as a background block, for underwater cities and such.
The only way it was really built wrong is the fact that it's in a valley and not on a hill. Farms in particular are a problem because any accumulation on the ground destroys crops. The door issues are simply because people leave them wide open.
Water only accumulates when a background is behind it, have you tried removing the background or tried replacing it with fences(any kind of fence)?
