My bathroom seems to be supplied by 3 pipes coming out of the floor and then through a wall into the bathroom like on the picture attached

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I can’t think of a reason why would you need 3 pipes?

I understand this question is quite low on details but would you have any suggestions as what the reasons might be?

  • 6
    Any or all of them may be doing something other than supplying water to your bathroom.
    – jay613
    Jun 18 at 10:31
  • 1
    There's no sense of scale other than that the one on the left looks smaller than the 2 on the right. It could be that one is supply for something and the other 2 are returns or vents.
    – FreeMan
    Jun 18 at 11:21
  • 1
    Put your ear really close to each pipe and have someone turn on/off the taps in the bathroom. If it is water then you could hear a constant swoosh. If any are sewage pipes then you'll hear more of a sloshing/trickle noise.
    – MonkeyZeus
    Jun 18 at 13:30
  • 4
    Where do they go in the bathroom? We only see three pipes going into a wall. If we see the pipes coming out of the wall and going somewhere, it might help.
    – crip659
    Jun 18 at 14:25
  • Where in the world are you? Are the bathroom floor heated?
    – J...
    Jun 18 at 20:39

The possibilities are endless, but these two are the most likely (assuming you know for sure that all of these pipes are supplying water for consumption, not part of a heating system):

2 warm + 1 cold: Hot water recirculation

Many houses have a loop system for hot water, where the pipes go from the tank to all the taps in sequence and then loop back to the tank again. A pump will be installed in the loop to keep hot water circulating. This ensures that the pipes are always full of hot water, so that as soon as you open the tap, the water that comes out is hot right away. This obviously offers convenience and water savings (no need to drain a lot of water that went cold in the pipes every time you need some hot water) at the expense of energy efficiency (heat losses from the piping).

2 cold + 1 warm: Rainwater/grey water system

Some houses nowadays have separate cold water feeds to the taps and the toilets. This lets you use collected rain water or recycled grey water (filtered waste water from sinks, baths and showers) for toilets and sometimes even the washer, saving a whole lot of potable water where it is scarce and/or expensive. A similar setup can also be used in houses with both a well and municipal water where the well water is not potable.

  • Also, one pipe could be a separate loop for baseboard/radiant heat.
    – MonkeyZeus
    Jun 18 at 13:27
  • @MonkeyZeus I assumed heating is explicitly out of scope of the question (which asks about "water supply pipes", so I assumed heating is already known not to be involved). If we throw heat into the mix, there will be many more combinations. Answer edited.
    – TooTea
    Jun 18 at 13:29
  • 6
    I wouldn't assume that. I think OP is soliciting all possible suggestions. Just because their knowledge stops at taps and toilets does not mean that they've ruled out learning new things. Besides, a heating loop is just as much of a supply as a recirc loop is.
    – MonkeyZeus
    Jun 18 at 13:35
  • 1
    Note that for environments where the house is normally heated, if the hot water pipes for the recirculation system are entirely within the heated portion of the house, then the energy for heating the water is not wasted. In that case, the heat-energy which is given off by the pipes is merely additional heat-energy which the general home heating system doesn't need to supply. It might not be as efficient, but it's not wasted. Obviously, the opposite is the case when the house is being cooled by an A/C system. In that case, there is the additional load on the A/C system of removing that heat.
    – Makyen
    Jun 18 at 17:18
  • 1
    @Makyen No waste in the winter, but waste in the summer when you don't need the heat. We went with a recirculator anyway, immediate hot water is so nice. Jun 19 at 1:01

In some homes, every fixture has a full run of pipe going back to a central manifold. In this kind of home instead of a single cold water pipe and a single hot water pipe going into a bathroom to service all the fixtures, there are separate pipes run for each fixture individually.

You don't normally run hot water to a toilet so if this is a half bath there would only be three pipes. Hot and cold to the sink and cold to the toilet.

  • Why bother with two cold water pipes? Easier to use one, and split inside the bathroom for sink/bath/w.c. for the cold.
    – Tim
    Jun 19 at 7:39
  • @Tim -- with one cold water pipe serving both, when you flush the toilet you lose some pressure at the sink. If the sink has a single faucet you'll get abrupt temperature changes. Jun 19 at 13:25
  • What's on the other side of the wall they go into? How old is the home? Does the house get water from both a well and the city? And lastly. Do they all feel the same temperature? I wouldn't expect any home to have them purposely outside a wall.
    – user113627
    Jun 26 at 3:19
  • @Tim ¯_(ツ)_/¯ It's just a style of plumbing where there are no couplers in the system and every line is just one continuous run of PEX run directly to a central manifold. It's kind of like how some electrical circuits are run directly to the main breaker with no other outlets or fixtures. The house I bought in 2005 was plumbed this way. Oct 23 at 6:04
  • @JustinOhms - obviously championned by those with PEX shares! Pobably necessitates a lot more holes being drilled, but I can't think of any advantages. Won't stop pressure drop, as it all comes from one mains.
    – Tim
    Oct 23 at 7:17

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