Topping up post boil

[Meatymc]

I had to replace my gas ring a few months ago having managed to snap off the tap and unable to get a replacement part. Since then - and bearing in mind exact same replacement ring/gas/set-up, the boil has been OK but not as vigorous as previously. Whereas I could dial it back on the old ring I'm now at full belt throughout the boil. Looking back through my notes, post-boil gravity readings are very slightly lower than before although marginally and not necessarily consistently.

So, as I've seen mentioned elsewhere, I'm wondering about reducing the boil volume and topping up after using same per ratio treated water.

This might result in using less gas whilst achieving a better 'boil' and also help temp reduction for pitching. However, if there are only pluses you'd expect that to be standard practice so, apart from not sterilising the additional treated liquid (which I could do separately and even beforehand) there has to be more reasons not to do it.

Thoughts?

[Mashman]

I have done this frequently in the past with no adverse effects. I used to keep a couple of bottles of spring water at hand. Using he beersmith dilution tool to calculate how much to add the get the desired OG.

M

[MashBag]

Yup. Top up post boil all the time.

Never seen the benefit of boiling extra perfectly drinkable water and making your head hurt with unnecessary math.

When water was not safe to drink that was a different matter.

[Meatymc]

Thanks guys - don't know I haven't thought of this myself!

Is there a limit/implications in how much is added in your experience - say up to 20%? And are you saying 'untreated' (as in Ashbeck for example) is OK??

[MashBag]

Yup 20% would be a good guide. I use tap, bottled would be fine.

[WalesAles]

Yup 20% would be a good guide. I use tap, bottled would be fine.

HaHaHa,
Meaty will use tap water because he is a tight Yorkshire Man.
No WAY will he purchase that expensive Ashbeck stuff.

WA

[MashBag]

I think he will right then... My inner Yorkshire man prefers tap too.

[Meatymc]

HaHaHa,
Meaty will use tap water because he is a tight Yorkshire Man.
No WAY will he purchase that expensive Ashbeck stuff.
WA

Damn right! Having said that if I'm treating the water for the boil I may as well use treated tap water to top up.

[Eric]

Tap water used here, with acid addition to remove all alkalinity.

[drjim]

Been thinking about doing this to get a bigger volume fermenting without needing to boil it all. Given rising gas/leccy prices it struck me it would be a good idea for standard size batches too, mash/boil at higher gravity and then dilute in fermenter.

[MashBag]

Yup. Why spend on fuel you don't need?