Answer to Puzzle #26: Gas, Water, Electric to 3 Houses

gas water electric puzzle layout26. A man has built three houses. Nearby there are gas water and electric plants. The man wishes to connect all three houses to each of the gas, water and electricity supplies.

Unfortunately the pipes and cables must not cross each other. How would you connect each of the 3 houses to each of the gas, water and electricity supplies?

This puzzle was also e-mailed to me through this website. I receive it once or twice a month so I thought it was about time I wrote out the answer. Unlike most of the problems on my site there is something of a trick to this one, and it's not exactly 'quant'...

Before reading the answer can I interest you in a clue?

Firstly, lets be sure we're clear of the layout:

gas water electric puzzle layoutclick to enlarge

Now it's just a matter of connecting up all the houses with all the suppliers...

Most people will get as far as connecting up 2 of the houses with three of the suppliers, and one of the houses with only two... At this point, unless you can see the trick, you get stuck.

gas water electric puzzle layout with two houses fully connectedclick to enlarge

So the trick now is to connect the final supplier to the final house.

In this case this is done by passing the gas supply to the second house through the first house and so not crosing any of the other pipes and cables.

gas water electric puzzle layout all houses connectedclick to enlarge

Easy when you know how ;)

NB- Whilst I've said that feedback is always welcome, I'm not desperately keen to receive abuse over this answer. The email below is maybe at the extreme end but it is not completely atypical.
Your answer is not correct. Your proposed solution is considered "cheating". The puzzle is not solvable. Would you want someone else's water, gas, or electric line running through your house? I don't think so. You should remove your proposed solution or at least remove your smug comment "easy when you know how" and replace it with a statement that the answer you proposed is not correct.
– Kathryn Brandon
As I told Kathryn my answer is correct, it is an answer to the question that I asked.

It may not be the correct answer to some other question that Kathryn Brandon thought I should have asked, but it answers my question just fine. And as for whether I'd want someone else's electric line running through my house... couldn't care less. Further I have been informed that this does actually happen.

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