Siphon (Syphon) Bath Water Without Sucking

In the UK right now we have a drought and also hosepipe bans. This instructable shows an easy way to siphon out your bath water so you can use it on the garden.

Some of us remember back to the big drought of 1976 and have memories of our parents sucking on the end of a garden hose to get the soapy bath water onto the vegetable patch. There's another way to do it which avoids the sucking!

This is based on the idea of siphoning by submersion.

Thanks are due to my friend Arthur who explained that siphoning doesn't have to suck!

Supplies

clear braided heavy hose (12.5mm or 1/2") - £12

in line release shut off valves for the garden hose (x2) - £9.50 for set of 2

a brick (or similar)

45 litre flexi tub (or similar) - £5

Step 1: Prime the Siphon

First attach the in line shut off valves to each end of the hose.

Open both valves and connect it to tap you normally use for your hosepipe.

Fill the hose with water and then shut off the valve at the end of the hose (away from the tap) and then the one near the tap.

You'll end up with your length of hose full of water. It's helpful having clear hose because you can see how much air is left in it (ideally none!).

Submersion siphon normally starts with submerging the hose into the liquid to be siphoned. Unfortunately this is quite fiddly with a length of hose in a bath tub so I found it works best to prime the hose first by filling it with water. For a 10m length of hose, this uses 1 litre of water (30ft and 2 pints is the rough conversion).

Note: I don't really need the full 10m (30ft) of hose and my life would be a lot easier if i cut it shorter - this siphon is for my friend's house so when i take it over i will cut it shorter

Step 2: Set Up the Siphon and Turn It On

Put the hose, still full of water, into the flexi tub and take it upstairs to your bathroom.

Put one end of the hose into the bath water and the other end out of the window.

Use the brick, which is wrapped in bubble wrap or an old towel to protect the bath, to hold down the hose end which is in the bath so it doesn't float around.

Take the flexi tub and put it outside ready to receive the water and turn the outside valve on.

Then go upstairs and turn on the hose valve which is submerged in bath water.

Now is a good time to think about how this works. I have about 6ft of hose from the bath to the open window and 18ft from the window the ground outside. The outside section of hose, full of water, has gravity acting on it and wants to fall to the ground. The shorter section has less gravitational pull by comparison so when the valves are opened the water will flow out of the bath and into the flexi tub. If it didn't work this way, the 18ft load of water pulling one way, and the 6ft load of water pulling the other way, would form a vacuum! I'm sure better explanations are available but I think this is basically how it works.

Step 3: Siphoning!

Here's the water siphoning out of the bath!

Step 4: Happy Trees

Happy trees!

In my area there has been some recent planting of trees along the streets. The young trees aren't surviving the drought without help so we use this water to give them a bucket each every day.

We also put some buckets near the River Thames to encourage people walking by to water the trees sometimes - it seems to work!

Step 5: Reduce Your Water Bill

In the UK we are charged for water, often metered. They calculate that 90% of what they supply is returned as waste water, so you also pay for waste water treatment too. If you use bathwater for watering the garden or street trees (or if you have a soak away) it can be worth telling your water company to see if they will give you a reduction on your bill.

I'm just trying this now, see - https://www.thameswater.co.uk/help/account-and-billing/understand-your-bill/reduce-your-wastewater-bill