Distilled water

Most definitely. I only use distilled water and my plants love it. The only issue you will run into is they are going to need some calmag at some point. But especially if you live in a place with hard water (I do), then RO is much better.

 

Distilled water theoretically should have a completely neutral pH of 7.0, but in reality distilled water comes in contact with air and can interact with it and change the pH slightly.

But the pH you need to be concerned with is your runoff pH, after the water interacts with your nutes, soil, amendments, etc. If your runoff pH is too low then you need to raise your input pH no matter what it's current starting point.

 

Research your local tap water a little bit dude...it will help you in many ways in the long run.

A story: When I got back into it, I threw all kinds of money at distilled water. Got sick of lugging jugs, so I bought an RO filter. Was growing soil and never checked the TDS or EC of anything...just mixed nutes with the amounts that seemed to work and went with it. pH'ed things appropriately, and yadada.

Visited a nice sized hydro shot at one point in there somewhere very close to me geographically...happened to be present for a rez change. How did it go? Hose hooked up right to the tap, faucet on, and tap water straight into the rez...no bubbling Chlorine, no magic hokus pokus juice added, no extra 100 gallons of water wasted to get 50 clean gallons out of a filter, no lugging of 50 jugs of distilled water to fill a rez.

The plants subjected to this commonly conceived as harsh treatment were thriving...looked fucking awesome...yielded fucking great.

What's my point, you ask? I understand.....that tap water around me is slammin. 27-34 ppm out of the tap. I didn't take the time to find out. In my eternal pessimism I assumed the worst, spent a bunch of money, and put a bunch of physical effort out there that was totally pointless.

Some people have shitty tap water and need to use RO or distilled. You may, and you may not, but a little research up front and you can know for sure what you are dealing with.

Wish I would have done mine in that regard...it's nice to pour water out of the tap, add nutes, water the plants, and walk away...if that option is available to you I'd highly recommend it.

 

Without getting to personal, here's a link to the EPA's data. If you trust your government implicitly, this might be enough for you....I personally dug further than this site, but it'll get ya started.

Local Drinking Water Information | Local Drinking Water Information | US EPA

There are many reasons for the EPA to bullshit you, and water regulation in this country (worldwide for that matter) is increasingly a corporate, private game. It's a crappy, scary deal for all of us peons out here in the world, but that gets me going in a direction no one wants me to bloviate about.

pH meter is necessary yes, but I'd also recommend getting a TDS meter. Here's a Hanna pen meter that works very well, is simple to operate, and costs about $40 with calibration solution included:

Hanna Primo TDS/EC Meter - Discount Hydroponics

With one of those you can see just how "hard" or "soft" your water is, plus they are useful even in soil to monitor the ppm of what you are adding. They're not required in soil, but nice to have for sure, especially if you start combining additives and other things into you nutes.

If you can afford a nice combo ph/tds/temp meter that's even better. If you get one, or can borrow one, just start by checking the ppm of your water. If it's very low (opinions will vary here, but I'd try it if it was less than 100ppm personally) you can give it a shot.

I'm not gonna make any promises cuz there are so many variables in growing, just my 2 cents from my personal experience.

In reading reports, you will likely find that even if you have low ppm tap, there are still some pretty nasty organic residues in there. Not a good deal at all, and I make absolutely no argument over that.

The only thing I would ask people to consider is that we seem to have very little problem consuming these chemicals ourselves in drinking water. Even our finest "bottled, natural, pure mountain, spring waters" (also tap by and large) contain these chemicals and we go on consuming them with little reservation; however, it comes to our pot plants and all of a sudden the concept of using our water becomes abhorrent...confusing to me.

 

Different brands of bottled water can have different pH's, usually around 6-7. Depending on the method used, the act of purifying water can lower its pH. Home-filtering water (Brita, etc) usually does this, often coming out slightly more acidic (~.5 lower). Check the pH of any new water you plan to use. Once you check it, you shouldn't ever have to check it again.

Always read the labels closely when choosing a brand. Some will say right on the bottle that it's the same water that comes out of your faucet. The unpurified waters are usually called "Drinking Water," as opposed to "Distilled" or "Purified" water.

 

ph meter is kinda pricey, especially if its your fisrt grow.
Just purchase the Ph paper strips. somecome in a roll like tape.
they are cheap and accurate.

im using distilled myself, even bought a distiller to do so

 

If you want to test your tap water, then you should test the actual water that comes out of your tap, not rely on statistics about what your treatment plant produces. Even assuming that the treatment plant figures are accurate, that's just their output which then has to travel miles through pipes that are made of different materials, could have seepage or leaks, so what ends up coming out of your tap and what comes out of someone else's tap on the same water system could still end up very different.

Google "test water sample" for lots of ideas.

Or, while a filter can be considered expensive, if you think of it not just for your MJ grow but for you as well then it's a worthwhile investment and will give you good water for your grow every time.

 

This. I find cal & mag deficiencies pretty early because of the distilled water, so there are other things you need to amend. It's worth it for people in my situation, I have water out of the tap PH'd at like 8.3.