Does Rainwater Need Treatment Before Use?

[MidgeSmith]

Hi,

probably a stupid question, but I am in the position to use water from my water butt to water my plants.  I would always do this outdoors, but I want to water indoor plants with it too. However, I am aware insects spawn in rainwater, it has been collected off the felted roof of my new shed where there will be some bird crap etc for it to wash through.

I will be putting each filled container in, or adjacent to my tent to reach room temperature before using it.  As it might sit for a few days between waterings, I am just wondering if incubating whatever is in it is a bad idea and it should be treated somehow?

Should I bother filtering it or dropping anything in it to kill potential life in it before using it for my indoor organic grow? If so, what?

I am guessing not, but any opinions gratefully received!

Midge

[mysticriver]

Just now, MidgeSmith said:

water from my water butt

I personally cant see a problem mate. The only issue would be whether the water is clean, or has the Ca:Mg balance been altered. And the pests thing you mentioned.

Have you stuck your conductivity pen in there to get an idea of the EC? That's what I would do. And the pH.

 

 

 

mysticriver

[MidgeSmith]

Just now, mysticriver said:

I personally cant see a problem mate. The only issue would be whether the water is clean, or has the Ca:Mg balance been altered. And the pests thing you mentioned.

Have you stuck your conductivity pen in there to get an idea of the EC? That's what I would do. And the pH.

 

 

 

mysticriver

 

Thanks @mysticriver,

no I haven't done anything with it at all yet. What would you hope to see in terms of EC?

I am going to be using it with organic soil, so hopefully the pH will be within the bounds of reasonable and therefore not a problem.

Cheers and thanks for the starting point

Midge

[latigid aikon]

Just now, mysticriver said:

or has the Ca:Mg balance been altered

Rainwater has almost no minerals at all!

 

So you'll probably have ca/mg issues.

 

Given that and the potential for bringing insects etc. in I wouldn't use rainwater indoors.

[mysticriver]

Just now, MidgeSmith said:

using it with organic soil

I dont know anything about that method. I dont even know if EC matters with organics. If the water has been through natures evaporation system, I would imagine it to be nearly 0 EC, but I could be wrong. Im not much help as I dont know if u need to add CalMag with organics. Sorry.

All the best mate.

 

 

mysticriver 

[dan6]

Quote from oldtimer1 

A few points:-

Rain water is fine, but it may contain spores of pythium, verticillium and the like, as do some mains water supplies, they thrive in anaerobic conditions.

All water allowed to stand for more than an hour or so will loose dissolved oxygen and should not be used to water plants unless its oxygenated, especially if the water temperature rises above 68f 20c, as dormant pythium spores will start germinating above these temperatures.

Its true cold water shocks plants, and round 20c is close to ideal, but it is best if it is fresh or an air stone is used to keep it aerated if stored for more than an hour or so. There is absolutely no reason for not using a mix of hot and cold tap water, the hot water will actually have a lot less carbonates than the cold water, but will hold less oxygen so filling your can with a shower head helps add oxygen and can be used immediately.

You may get away with storing water for days on end for several grows without grief, but sooner or later pythium will strike, you really don’t want that to happen. If you want to store water for over an hour or two, get an air pump/stone, it only costs a few quid and will save a lot of grief at the end of the day.

Regards

Dan

[MidgeSmith]

Thanks @dan6,

 

that is my fear - totally love your profile pic btw

 

I think the problem I have with tap water is that where I am the water is very soft - so I am not sure about the cal-mag levels.  Also, it is quite rich in chlorine and possibly chloramines, though I don't know.

I have cal-mag I can use (though I'd have to figure out if I actually need it or not somehow) and I am planning to get hold of some chlorine remover, such as ecothrive neutralise to deal with that. So those issues should be a problem if I do use tap.

I'm glad I wasn't being mad - being concerned about using rainwater indoors!!!

I guess if I were to treat the rainwater, I would be back in the same position as if I had used tap water anyway...

 

Edited December 8, 2021 by MidgeSmith

[latigid aikon]

37 minutes ago, dan6 said:

There is absolutely no reason for not using a mix of hot and cold tap water

The EC of my hot water is higher than my cold water, even when it has cooled so they are the same temperature.

 

I suspect it might be due to the sacrificial anode dissolving.

 

Some hot water systems may be OK but mine definitely has additional dissolved substances compared to my cold water.

[MindSoup]

The need to remove chlorine/chloramine from water is a myth, it can in fact be detrimental, so save your money. If your soil is ammended properly Cal/Mag ratios in your water shouldn't really matter either, things like rock dust that are mixed into the compost contain all that stuff already, so its pretty unlikely you will need it. PH also doesn't really matter (within reason) as your soil will buffer it and a healthy micro herd will control it anyway. 

 

As for using rain water, I would say it should be absolutely fine for your application, I'd probably just use it and hope for the best myself, but it would be an idea to get it tested just to make sure there's nothing weird going on. There's a popular company that people on here use to test their water, the name escapes me right now, perhaps someone else can remember it ?  

 

I would never question anything said by OT1, I'm sure pythium is a potential risk, but for the record, since I've been indoor growing (about a year so) I've only ever watered my plants with (tap) water thats been stood (in a closed bottle or my res) for at least 24hrs. Maybe I've been lucky. 

 

Sods law I get home from work to find wilting plants

Edited December 8, 2021 by MindSoup

[Kush Lover]

1 hour ago, dan6 said:

There is absolutely no reason for not using a mix of hot and cold tap water,

 

I would say I have to champion this strategy and it works great for me. After a few trial and error runs working out the ratios I now use x amount of cold and x amount of hot and it gets it bang on 20c and ranges between 5.7 - 6.2 ph which is perfect for my coco grows. 

[latigid aikon]

Just now, MindSoup said:

I would never question anything said by OT1

Me neither horticulturally but he isn't a plumber! My water heater definitely adds to the EC of my tap water, which isn't to say that all water heaters will do the same but some might.

 

I just googled sacrificial anode and apparently they are made of either aluminium or magnesium.

[MidgeSmith]

Thanks for the reply @MindSoup,

 

If  Chlorine / Chloramines don't matter, then I may as well use tap.  I have always used tap in the past, but let it site 1 - 3 days to let excess chlorine evaporate off hopefully, though I hear chloramines don't. With tap water, I am certain that is ok.

Have you a citation for the chlorine/chloramine thing being a myth.  Sorry to ask, but it seems a little contentious.

I will be starting in peat plugs, planting into light mix, then repotting into supersoil such as Ecolife by Ecothrive, so you are right about the calmag - stupid brain, I forgot that aspect, so thanks again for the reminder!!

I think you are probably right about the rainwater being low risk, but I'd probably feel safest using tap if there is any extra risk.  I just need to find some definitive about the chlor part to feel 100% confident. At the moment though and having just read more about it, I am 98% confident that is right too.

 

I have an airpump and waterstone I used to use for brewing that I can move over to the grow to oxygenate before watering if the water has been sitting, that's probably a good call

Thanks fellas.  I guess the answer is either is probably fine, with a leaning towards tap from the position of avoiding unwanted spores and larvae.  I'll be back with the next query or annoying deficiency photo or worry in the next few weeks

Edited December 8, 2021 by MidgeSmith

[Guest]

2 hours ago, dan6 said:

There is absolutely no reason for not using a mix of hot and cold tap water, the hot water will actually have a lot less carbonates than the cold water, but will hold less oxygen so filling your can with a shower head helps add oxygen and can be used immediately.

 

I did experiment with using tap lukewarm water around 18/20C with hydrogen peroxide (H2O2). Roughly, I used 6-7 drops of  hydrogen peroxide per 200ml of water. Can confidently say it didn't harm plant at all. On the contrary yellow spots on leaves disappeared. Back to old watering (let the water stay in tank for 24 hours)style and spots back again. 

Edited December 8, 2021 by Canna Denfour20

[MindSoup]

48 minutes ago, MidgeSmith said:

Have you a citation for the chlorine/chloramine thing being a myth.  Sorry to ask, but it seems a little contentious

 

Was advised by @blackpoolbouncer, trust his word/knowledge do haven't done my own research. I used to use neutralise, I know don't, I've noticed no change. 

 

[MindSoup]

@latigid aikon My hot water comes out a bit cloudy and tastes different to the cold tap even when its cooled down, no idea whats in it but it sure as fuck isn't going anywhere near my grow tent .