Spring water is sold in those milk-jug style gallon sized containers. Again- not really that weird to have one or to carry one in your backpack.
Water : Publix.com
RT said they had a gallon of water with them (that he must have been carrying since he said BT went missing without any water) (
BBM):
"
Robert says they had taken a short trip in their camper when they decided to pull up and go for a 2-mile walk to explore rock formations. They took a pack, beer and a gallon of water, and Barbara was wearing a bikini, hiking boots with black socks, and a red-and-white baseball cap."
Husband of Woman Who Vanished During Mojave Desert Hike: 'I Just Want Her Back'
A gallon of water weighs about 8.3 pounds.
Gallons to Pounds [ water ] (gal to lb [ water ] ) Conversion
Beer and a pack, less than that, unless they were also carrying a gallon of beer.
IMO and MOO, as an experienced walker/hiker who goes on walks/hikes with other experienced walkers/hikers, and in the desert as well, all of us:
(1) put considerable thought and effort into minimizing weight we're carrying on a walk/hike of any length in order to lighten our load and minimize burning of calories, especially on uneven/hilly/steep trails and terrain, and in the heat of the day.
(2) would carry a smaller personal reusable plastic, metal or glass water bottle with a screw cap/lid (typically 12 - 22 ounces) for a short walk/hike, or a Camelbak pack (typically 50 - 100 ounces) for a longer walk/hike, or, if 'on the fly' without our usual walking/hiking gear to hand, individual sized disposable plastic bottled water (typically 8 - 16 ounces). Often with electrolyte powder added, especially when it's hot out, as an extra measure to prevent dehydration. You can carry the smaller ones on your person (in your hand(s), in the waistband of your trunks/shorts/pants/bathing suit bottoms/bra/bathing suit top, under your hat, in a strap around your arm or leg or waist) and if refrigerated or put on ice beforehand, they will help keep your body cooler for longer than carrying warm water in a pack on a hike in the heat.
(3) would not have one person alone carry all the water (8+ pounds, presumably in a plastic jug with one handle) for two people, which would be the heaviest item to carry on your person, either in a pack that would either take up a lot of room, not leaving much other room (for the camera and the beer), or would be difficult to carry in your hands on a walk/hike of any length, and juggle and have to set down on the hot ground while stopping to take photographs or go exploring/check out rocks.
IMO and MOO, as an experienced hiker, starting out on a short (2.2 mile) walk/hike with only one person of the two people hiking together carrying 8+ pounds of water in the heat of the day in the heat of the desert would be:
(1) a tiring amount of weight to be hauling in one place by one person in a container not designed for the activity and terrain.
(2) an indication that the walk/hike was not well planned / standard protocols were not followed since two people can (and did in this case) get separated from eachother and the one source of water available to them, and in such extreme conditions.
According to RT, they apparently had already thought out the possibility they may get separated since that is the reason he gave for hiding the key to their truck/RV under a rock nearby instead of carrying it on either of their persons, so whomever reached there first would be able to get in if on their own/ahead of the other and in need of shelter/bathroom/shade/food/a cool place to rest, etc.
Therefore, it seems to make sense that they would have put the same amount of thought into each of them having access to things needed to survive out there for any length of time, i.e., water (and a cell or satellite phone, actually, in case of emergency) on their walk/hike.
According to RT, he said BT had 'a beer in her hand' when she disappeared. However, experienced desert walkers/hikers and guides you can read about day hiking like this one recommend each person always has their own water supply (some parts
BBM):
How Much Water Do You Need for Day Hiking?
It’s important to bring water with you when you go day hiking to replace the fluid you lose to perspiration, help keep you more alert and flush waste products out of your body. Not bringing enough water can lead to discomfort, while bringing too much can slow you down. How much water do you need and what’s the best way to carry it?
1 Liter every two hours
If you’re actively hiking, it’s good to drink about 1 liter (32 ounces) of water every two hours. That’s a good rule of thumb based on my experience hiking year-round and in a wide range of climates. You might need more or less depending on the temperature, humidity and body weight, but that’s a good estimate of what you’ll need to carry if you can’t refill on your route.
Water bottles are best carried where they are easily accessible on the outside of a backpack rather than being buried inside it. Backpacks with stretch side pockets are convenient, so you can reach back and grab a bottle to sip from while walking.
[.....]
Does it have to be water?
No. You can drink any non-alcoholic fluid. Water is usually cheap and easily available, but you can also drink tea or juice if you prefer, or add an electrolyte mix to your water...
[....]
https://sectionhiker.com/how-much-water-do-you-need-for-day-hiking/
IMO and MOO, RT saying that BT was not in possession of water (not to mention a communication device, ID/wallet, food or other supplies) when they 'became separated' and she went missing on their 2.2 mile walk/hike while he was carrying all their water supply and other items himself, is not consistent with how other experienced desert walkers/hikers take precautions, nor does it follow the 'buddy system' of staying together that I would especially expect a couple to adhere to when walking/hiking alone in the desert in an area they had not hiked together before:
"
If you are planning a trip into the desert during the months when high temperatures can occur, this is usually June through September, with July and August being the hottest. Consider if this trip at this time of year, is really necessary. The most elaborately planned desert trip could result in your being placed in a survival situation. Desert temperatures can rise in excess of 120 degrees.
The following tips will help you stay safe on a desert hike.
ABSTAIN FROM HIKING DURING THE HOTTEST PART OF THE DAY. [....]
REMAIN HYDRATED. SERIOUSLY—DRINK A LOT OF WATER. [....]
REPLENISH ELECTROLYTES. [....]
FIGURE OUT HOW TO RECOGNIZE SIGNS OF HEAT-RELATED ILLNESSES. [....]
KNOW ABOUT FLASH FLOODS. [....]
DRESS APPROPRIATELY AND TAKE LAYERS. [....]
KNOW YOUR LIMITS AND REST OFTEN. [....]
WATCH FOR WILDLIFE AND KEEP YOUR DISTANCE. [....]
USE THE BUDDY SYSTEM. [....]
LEAVE YOUR ITINERARY WITH A FRIEND OR RELATIVE. [....]
MAKE SURE YOU ARE EQUIPPED WITH EXTRA SUPPLIES. [....]"
POINTERS ON HOW TO HIKE THE DESERT SAFELY