Connecting 2 water tanks?

[StephenStephen]

I have a water butt and a large rectangular water tank. I've had them connected together with a (slightly random) 15mm speedfit arrangement.

I want to upgrade it to a wider bore connection with a flexible pipe.

It's not possible to get to the inside of the big rectangular tank, but I think the walls are thick enough to screw a connector securely into.
I'm thinking to drill a bigger hole then use a brass screw-in fitting with ptfe, or with some kind of waterproof sealant?
The water butt I can (though it's a stretch) get to the inside (if I hold the nut on an adjustable wrench).

I'd be really grateful if anyone can suggest how to find the brass fitting, pipe and fitting at the other end, that will play nicely with each other.

Thanks for reading, and any thoughts or suggestions, Stephen

 

[HERTS P&D]

This might work with extra fittings to connect to your pipe.

https://www.amazon.co.uk/GARDENA-Push-in-Tank-Connector/dp/B0DMFB1R73/ref=asc_df_B0DMFB1R73?mcid=761d6f7b50743f3d9083b13b96a5dcf5&th=1&psc=1&tag=googshopuk-21&linkCode=df0&hvadid=787352598229&hvpos=&hvnetw=g&hvrand=6331410256678179243&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1006625&hvtargid=pla-2398806087582&psc=1&hvocijid=6331410256678179243-B0DMFB1R73-&hvexpln=0&gad_source=1

Andy

 

[Mottie]

This is how I’ve connected mine up over the allotment. Not my actual butts but the same system.

 

[CountryFan]

What is the rectangular tank then? Any photos/web links?

 

[StephenOak]

What is the rectangular tank then

Probably an IBC

Intermediate bulk container - Wikipedia

en.wikipedia.org

The hole (middle of the top) is c. 8" in diameter, so fine for getting the contents in/out, but no where nearly enough space to reach in and secure the inside of a fitting.

A neighbour has some at the bottom of his garden and pumps water from his water butt into them, so he has plenty of water for his plants.

AFAIUI some are only used once (or a small number of times) are are then disposed of, so they are relatively cheap.

 

[StephenStephen]

What is the rectangular tank then? Any photos/web links?

I bought it from the dump a few years ago, I can take photos in the morning

 

[StephenStephen]

What is the rectangular tank then? Any photos/web links?

The thread on the outlet is not in good condition, and is smaller than I want it.
I've ordered the connector Andy suggested - it looks intriguing

 

[Mottie]

I have also connected several tanks together, no drilling required, using just a piece of pipe in an upside down 'U' as long as you fill and prime the pipe before putting each end into each tank. Fill it up, bung the ends, get each end under water before removing the bung. Also, make sure the ends are cut at an angle so that they can’t block up if they touch the bottom and obviously, never let the tanks run dry.

 

[foxhole]

I have also connected several tanks together, no drilling required, using just a piece of pipe in an upside down 'U' as long as you fill and prime the pipe before putting each end into each tank. Fill it up, bung the ends, get each end under water before removing the bung. Also, make sure the ends are cut at an angle so that they can’t block up if they touch the bottom and obviously, never let the tanks run dry.

So a siphon?

 

[big-all]

general thoughts

increasing size wont increase the pressure as that's dictated by volume and elevation[weight]
it will help the flow rate but iff its just a gravity fed hose in the present lack off rain 15mm would be more frugal

 

[StephenStephen]

So a siphon?

Thank you,

Yes I did think that'd be the easy and sensible approach, but access is difficult between the tanks, so I was thinking that charging (and keeping charged) the pipe would be tricky.
Also, the tanks do regularly run dry.

 

[StephenStephen]

general thoughts

increasing size wont increase the pressure as that's dictated by volume and elevation[weight]
it will help the flow rate but iff its just a gravity fed hose in the present lack off rain 15mm would be more frugal

Yes, it's the flow rate between the 2 tanks I'm looking to increase - the area of roof feeding it is quite small, so I tend to pump fill them with a larger bore pipe from another rainwater tank, into the front tank, and the water isn't completely clean, so I'm keen to know that the link between the tanks won't get blocked.

 

[StephenStephen]

This is how I’ve connected mine up over the allotment. Not my actual butts but the same system.

View attachment 420071

Yes, that's what I'm looking to do.