Using filtered water, like that you can get from a Mavea water filter, improves and taste and experience of your jams, pickles, and jellies.
As many of you have come to know, water is often a primary player in canning. Most pickling recipes call to dilute vinegar by half. We can whole fruit by making a syrup of sugar and water. When I want to include an intense flavor (like ginger) in a preserve, I blend it with some water before squeezing it through some cheesecloth to get a potent little brew.
In all of these recipes, I make a point of using filtered water. Preparing fruits and vegetables for canning is often a process of cooking down and concentrating your ingredients. I really don’t want to concentrate any extra crud or crap in my finished product. I live in an older apartment building, so who knows what kinds of funky particulate matter is in the H2O that comes out of my tap? It’s just one of those steps I like to take to ensure that the quality of my product is as good as I can make it when I go to open those jars six or eight months later.
Edited to add: There’s been a little confusion in the comments. I don’t use filtered water in my processing pot. I only use it IN the canning recipes. Regular tap water is fine for the outside of the jars.
For most of my adult life, I’ve been a Brita water filter user. Recently, I had an opportunity to try the new Elemaris filter and I really like it. It’s made by Mavea (which is part of Brita), is entirely BPA-free and the filters are recyclable. It has a meter on top that tells you when the filter is due for a refill and the lid is designed so that you can simply position it under the tap and fill, no need to remove a piece or flip open a flap. They’ve even created a nifty blog called Inspired Water to help spread the word about this product.
Disclosure: Mavea gave me that black Mavea water filter you see above. I’ve also filmed a series of canning videos with them that will be appearing in the next few weeks. No money has changed hands and I wouldn’t say nice things about their pitcher if I’d didn’t genuinely like it.