We filter our drinking water at home, though it’s not because there’s a risk of giardia or heavy metals in the tap water where we live. Personally, I just like the taste of water that’s been run through activated carbon. If your own water is safe from heavy metals, but you still like the way water tastes when it’s been through something like a Britta filter, there’s an easy way to convert the filter to be reusable, saving a ton of waste and a bit of money.
Your standard Brita pitcher filter contains two components, an ion exchange resin that is used to reduce heavy metals, and a bunch of activated carbon which is used to remove chlorine and various organic impurities that can affect the water’s quality and taste. I’m not sure about how to go about recharging or replacing the ion exchange resin, but activated carbon is available in any pet store, where it is sold for aquarium water filtration.
Below is a link to an Instructable which shows you how to convert a Brita pitcher filter into a refillable carbon filter. You’ll only need a couple standard tools to do the conversion, and when it’s complete you’ll have great tasting water, you’ll be able to do refills for about 50 cents a cartridge, and you won’t be tossing a one-time-use hunk of plastic in the landfill.