BWCA woman drinking water

Drinking Water in the Boundary Waters Without Getting Sick (5 Rules to Know)

I’m generally not too worried about the Boundary Waters drinking water. Reports of Giardia and other water-borne illnesses in the Boundary Waters are rare, and with some conscious effort, can be confidently avoided.

This article is going to cover water treatment, filtering, and how to collect water in the BWCA — so you can confidently hydrate while traveling in the Boundary Waters.

Can you drink lake water in the Boundary Waters?

BWCA water is considered quite pure in that no sewer plants dump into any of it and all the water flows out as it’s the top of the watershed. There is common sense in avoiding water that looks stagnant and dirty. But for the most part, you’ll be just fine dunking your bottle into the deep part of the lake and drinking it right up.

Back in 1968, the Iowa Academy of Science performed an extensive study of the pollutants in the Boundary Waters water. What they found was that much of the water, if untreated, did not meet standards for US Public Health. However, they weren’t sure if that really mattered much.

The same study also found that, in general, the more remote the lake the better, in terms of bacterial count. It varied even on the same lake from the portage site to the middle, deep part of the lake (so get your water out in open water, and not right off a portage).

The fact is that drinking water from the wilderness is a different experience than turning on the tap at home. And there are certainly pros and cons to it.

Is there Giardia in the Boundary Waters?

Giardia is uncommon in the BWCA. While you can get a waterborne illness almost anywhere, it is quite rare in Northern Minnesota. While you obviously want to avoid it, you likely won’t become sick while in the BWCA, as it takes one to two weeks before becoming symptomatic.

My rule of thumb to avoid Giardia in the Boundary Waters is to get water where I can’t see the bottom and avoid stagnant bays or anywhere it looks like beavers or moose would like to hang out. Of course, you can’t be 100% certain just by looking at the water that there are no pathogens in it, but starting with the cleanest looking water is a good rule of thumb (at least it has worked for me the past three decades).

The rules of hydration

Drink water (and lots of it)

By far, dehydration is the biggest risk you can take in the wilderness. Be sure to drink water. Do not be afraid of it, and if you don’t like the taste — add a scoop of electrolytes! Whether people are nervous about it or just not in the practice, it’s not uncommon for novice campers to avoid drinking lake water. But it’s essential that you make sure the people in your group stay hydrated.

Get your water from deep parts of the lake

Whether you filter or not (you should probably filter), filling your water bottle from the middle of the lake is going to be safer than in the shallows. The rule of thumb is to get your water from parts of the lake where you can’t see the bottom and try to reach down into the lake at least to your elbow to fill up.

Filter your water (or treat it)

I recommend you bring a portable water filter, and it’s not a bad idea to have some way to treat your water as a backup (gear fails). My go-to Boundary Waters water filter is this 4L gravity water filter. It has good volume and is super simple to do — no pumping or anything — just fill up the one bag and let gravity pull it through the filter into the “clean” bag.

For a lighter option than a filtering system, you can use iodine drops or tablets to sterilize water. Some people don’t like the taste (I’m used to it and it makes me feel nostalgic for the backcountry), so is a good opportunity to push electrolytes.

You can obviously boil water to great effect, too, but that takes quite a lot of time and fuel; best suited for tea or coffee.

Add electrolytes to your water

When you’re paddling hard, it’s important to replace your electrolytes in order to maintain energy. There are a lot of powdered electrolyte options out there. My wife loves LMNT for its simple ingredients and good taste. I’m a fan of just adding a 1/4 teaspoon of salt and a 1/4 teaspoon of magnesium (“Natural Calm” is a great magnesium source and is lightly sweetened with stevia).

Use the lake as a fridge

One complaint of drinking water in the Boundary Waters is that it’s not cold, especially if your water bottle has been sitting in the bottom of your canoe in the sun all day. One way to keep your water at least the temperature of the lake is to keep your bottles in the water. Make sure they’re strapped onto your canoe somehow and let them float.

Top water in the BWCA is usually around 70 degrees in the height of summer, so it won’t actually be that cold, but won’t be hot!

Hydrate and be healthy

The Boundary Waters is a place of bountiful beauty, clean water, and abundant wildlife. If you go in at the right times, it might even provide blueberries and raspberries to top your wilderness pancakes. You don’t want to damper your excursion because of your uncomfortable drinking the water. You’ll regret it, I promise. So take these precautions, stay hydrated, and enjoy your trip.