48-hour Water Consumption Backpacking on Catalina

My kids and I just got back from backpacking from Two Harbors to Lands End and back on Catalina Island off the coast of Los Angeles. As the designated campsite, Parsons Landing, has no fresh water we carefully tracked our usage; here are the details / results:

Hikers:
Dad, age 47, 180 pounds
Son, age 14, 130 pounds
Daughter, age 11, 100 pounds

Day 1:
We left Two Harbors at 11:30 am and walked 7.7 miles in 2.5 hours to Parsons Landing. Elevation gain and loss was 367 feet (this was the easy way). Distance and elevation gain/loss are from Google Maps. Started with 5 liters and only used about 1.2 liters. At the campground we collected 6 gallons of water from lockers (which we paid to have delivered). High and low temperatures were 54 and 69 degrees F.

Day 2:
Left Parsons Landing at 7:00 am, walked to Lands End and back (maybe 10 miles) in 5 hours. Elevation gain/loss was 3000 feet. Distance and elevation are from a track I made in Google Earth. I trust the distance but think the elevation is too high as the route near Land End was off trail along a crest with steep drops on either side. Started with 2 liters and came back empty but not thirsty. High and low temperatures were 58 and 90 degrees F.

Day 3: Left Parsons Landing at 6:30 am and walked 6.7 miles back to Two Harbors in 3.25 hours. Elevation gain/loss was 1795 feet (this was the hard way). Distance and elevation gain/loss are from Google Maps. Started with 5 liters and used half. High and low temperatures were 58 and 90 degrees F. Note that we left 3 gallons of unopened water at Parsons for future hikers.

Water Summary for 48 hours:
5 L + 6 gal – 3 gal – 2.5 L = 13.9 L total for 3 people for 2 days or 2.3 L per person per day. This amount includes water used for cleaning up, brushing teeth, etc. However, cleaning up water was minimal as we brought dried out wipes that we re-hydrated. Also, our food had more water than usual as the first night we grilled sausages, asparagus and green onions over the fire and the second night we made cheese quesadillas over the fire.

Conclusion:
We used way less water than I would have thought. However, so many variables go into water consumption that you should not use anyone else’s data to determine how much water you need.