What is the meaning of “drains” in here?

Question

"I expect someone lives there in secret, only coming in and out at night, with a dark lantern. We shall probably discover a gang of desperate criminals and get a reward. It's all rot to say a house would be empty all those years unless there was some mystery."

"Daddy thought it must be the drains," said Polly.

"Pooh! Grown-ups are always thinking of uninteresting explanations," said Digory. Now that they were talking by daylight in the attic instead of by candlelight in the Smugglers' Cave it seemed much less likely that the empty house would be haunted.

I looked in the dictionary and found that drain = pipe, but I don't know what it really means here.

Answer 1

First, you need to look in a better dictionary. A drain is a pretty specific type of pipe; in fact, it needn't even be a pipe (e.g. so-called "french drains" around a house, which are gravel-filled ditches).

drain (n): a means (as a pipe) by which usually liquid matter is drained

drain (v): to draw off (liquid) gradually or completely

Basically, in a house, the drains are where the water goes when you flush the toilet or pour the pasta water into the sink.

Second, there's a bit of cultural knowledge at play here: English houses, especially old English houses, were notorious for having bad drains. The drains would clog often, and when they weren't clogged, they'd let in sewer gasses (or worse, leak suspicious fluids onto the kitchen ceiling), and even on their best days they'd be slow as molasses - taking hours to drain a tub, for example. Fixing the drains would usually involve digging up the entire basement, exposing half the floor rafters, and doing unsightly things to the parlor walls and ceiling; basically, more trouble than it was worth unless you already lived there and had no choice. Hence, it's entirely plausible that a house with bad drains would sit uninhabited for years.

Answer 2

You interpreted drains correctly in that it means pipes.

It seems that the characters think that because the house has been empty so long that it must be haunted. Polly explains that her father said this is likely due to the drains in the house.

Edit: Updated answer to reflect @cindi's information. Nice catch. Thanks!

Answer 3

In this case, it means the waste pipes leading to the sewers.

Answer 4

Seems to mean that no one wants to buy the house because the drains are bad and that explains why it has been sitting empty.