For the most part, there is abundant water along the CT. I have done the trail several times in varying drought versus rainy years and have never carried more than 2 liters. I use two one liter bottles and a ceramic filter. Most of the time I carry the second bottle empty. It is used for additional camp water but is really only necessary in a few dry stretches. When I encounter water, I stop and drink a lot of it, fill one bottle, and carry on. When that bottle is empty I start looking for water again. The exceptions are:
Segment 2. You need to go about 17 miles from the S Platte to the first reliable water in Segment 3. I fill two bottles at the river and do the 17 miles in a single day. There is emergency water available near the end of segment 2 at the firehouse. Read the guidebook for details.
Segment 18 gives some people problems but I have always found water in Los Creek at mile 9.0. If the creek is not running at the point where you turn left and uphill, stay low and follow the stream bed a bit (don’t turn). There is a muddy pond about a half mile along the creek if needed but I’ve always found good water in the creek itself. I’ve camped at this location a couple of times.
Segments 26-27 have a 20 mile dry stretch from mile 8.4 of 26 to mile 19.4 of 27. There is a really good spring right at treeline at about mile 7.1 of Segment 26. I fill up there and drink a bunch. Then I dry camp at about mile 10 or so of Seg 27. You should get as close as possible to Indian Trail Ridge ahead without actually going up there. Hit the ridge first thing in the morning and you will be at good water by noon and off of the ridge, which is a lightning magnet in the afternoons. A third liter of camp water would be nice for this stretch but as I said, two has always worked for me.
As far as water quality is concerned, be aware that Giardia is carried by beavers and is widespread in Colorado. Any stream that has a beaver pond on it should not be trusted. I will drink directly from springs but always filter stream water.
bearcreek