I should say the sonoff is to set up automatic watering 

Am thinking of doing the exact same thing to pump water from two butts on the annexe and workshop (will connect them together via gravity when we do the patio) to two interconnected ones at the end of the garden.

 

The issue will be detecting when the butts at the end are full, of course.

 

Hozelock do a (obviously chinky rebadge) Water Butt pump, the issue I think with 'storm' or flood submersible pumps I think is that they are not designed to maintain a sensible pressure - just as much pressure as possible into the biggest pipe possible?

The other chinky waterbutt speicifc pumps do look cack though.

 

Do you have level access to the tanks? If so then there is an alternative hozelock model that might be more suitable, especially as it works by switch, not float.

 

https://www.amazon.co.uk/Hozelock-7606-0000-Garden-Pump/dp/B078ZS6VLV/ref=sr_1_7?dchild=1&keywords=hozelock+pump&qid=1586856669&sr=8-7

if your pumping id use float switches up to your head height if thats what your planning

I was thinking I could use a few of these https://www.ebay.co.uk/itm/CARAVAN-MOTORHOME-12V-SUBMERSIBLE-WATER-PUMP-COMET-VIP-PLUS-20L-PER-MINUTE-NEW/183948851003?epid=1223130493&hash=item2ad434b73b:g:dBUAAOSwv0tU5fki

 

I already use them for refilling my fish tank and when need to refill the adblu in the Merc. I know theyre not high pressure but I am thinking do I need high pressure if its doing it automatically then it can do it for longer 

Depends how clean the water is I'd say.

Wouldn't think they would last long for grey water tho?

2 minutes ago, datadiffusion said:

Depends how clean the water is I'd say.

I think the water isnt to bad its a big tank, if you read the reviews there is a guy that uses it in his allotment to pump water up hill

1 minute ago, sixwheeledbeast said:

Wouldn't think they would last long for grey water tho?

The one I use for my fishtank is 7 or 8 years old, it is used for clean water only (with additives) but I have left it submerged for weeks in the past 

I got one of these when stuck as the previous 'dark water' pump failed but its been in for over a year now

 

https://www.toolstation.com/einhell-ge-dp5220ll-2-in-1-clean-and-dirty-water-pump/p91077

It's things like small bits of grit and dirt that wreck the pump tho, adblue or tap water would be different.

Something similar to what JW posted would be more suitable they often have a float switch attached to them, they ain't supposed to be permanently fitted tho.

I know its not supposed to be permanant but if i get 3 years out of it ill be happy. I expect the seals to fail on it to be fair with whats its shifting. The grunfos that I bout previously only did 4 years