Update on black bottles for hot water

[TrainChaser]

Yesterday, September 28, I did my matte-black-painted one-gallon plastic water bottle experiment for a source of hot water without a stove or fire.

* The temp was 70F, clear, sunny.
* The bottle was a clear plastic Crystal Geyser from the local Dollar Tree; I had melted a hole in the lid with a hot nail for the soil thermometer, and dropped the thermometer shaft into the hole.
* The surface was an old black asphalt driveway with weed dust stuck in the cracks.
* The control was an unpainted bottle of the same kind (label turned away from the sun).
Due to my faulty memory problems, I put both bottles in position the night before.

Results:
I forgot about them until noon.
* At noon, the temp in the black bottle was 105.
* At 1 p.m. (I set the kitchen timer) the water temp was 110.
* At 2 p.m. the water temp was 110.
* At 3 p.m. the water temp was 110.
* At 5 p.m. the water temp was 105.

That showed a 40-degree rise in temperature from the ambient air temp.

The control bottle was a complete waste of time because I forgot to put a hole in the lid to measure the temperature of the water.  I could have just unscrewed the lid, but I didn't.

I left the thermometer in the black water bottle (I forgot it) and when I went out at 9:30 this morning to retrieve it, the air temp was 50 and the water in the bottle was 60.

My hot water heater (set to the lowest normal setting to save energy) hadn't been used yet this morning, so I ran the hot water tap to wash dishes, filled a ceramic mug and let it warm up for a minute, then dumped it and refilled it with more hot tap water and stuck the thermometer in it:  115F.

The Web says the ideal hot shower temperature is somewhere between 100-110F.

More work is needed.
* If the air temp had been 90F, would the temp in the bottle still have gone up 40 degrees?
* If the bottles had been laid on their sides (exposing more surface to the sky), would that have made a difference?
* If I had washed the driveway the day before to clean off the weed/wood debris to make it blacker, would it matter?
* If a curved, foil-covered arc stood  immediately behind them, would it have made a difference?  Or a pile of bricks formed into a short wall?  Or a pile of bricks painted black? Or set close to the front of the S-facing garage door?
* SODIS says the maximum volume for that method of water purification is 2 liters/quarts; would the smaller size have changed the results?

Next time, I will prepare the clear bottle properly and compare.  I would hate to discover that I had painted 50 bottles black when I could have gotten the same results from clear ones.  Of course, unpainted, they would be subject to more UV damage, but I could paint them in pretty colors instead so they didn't look like goldfish caskets.

I should do this with the four seasons and see what happens.  I wouldn't be hoping for much in winter, but the black paint might prevent the water from freezing on marginal days.  That's W WA winters, not ND winters.

 

[jimindenver]

If you look to see how a solar cooker is used you will see that they always have a way to trap the heat. They use a oven bag around the black cooking vessel and you could use any clear bag around your bottle.

 

[Marie]

Train Chaser, doesn't the SODIS method of purification utilize clear bottles? Is it the heat, or the solar Rays that actually purify the water in the SODIS method

 

[wagoneer]

I need to say this,,, you are funny and that was a good read thanks for the info as well.

 

[TrainChaser]

Marie, yes the SODIS method uses clear bottles with labels removed; I was mainly referring to the size/volume of water. They said it doesn't work with gallon bottles, so I am assuming that the volume was a drawback. Next experiment, I should include a clear and a black-painted 2-liter bottle.

And, I think it is a combination of the heat AND solar rays that does the job. Sunlight, by itself, kills many organisms. For just hot water, we would only need the sun for heat.

Jim, that is another consideration, but probably more suited to water purification. If a person COULD raise the temp as you suggest, it would certainly enlarge the area for the usefulness of the SODIS method, especially, but might also be useful for just hot water in cooler weather. Thank you for the idea!

 

[SternWake]

I find water temps exceeding 114.5f degrees to be too hot to bathe in.

Try painting only half the bottle black and aiming the clear side to the sun, see if it heats faster.

 

[Odyssey]

Where were you when we did those science fair projects?

How did you paint the bottle? I went a little overboard on my weed sprayer. Washed it first with Dawn and a Scotch-Brite pad to remove all shine, then used a Krylon primer spray and 2 coats matte black plastic spray, sanded in between.

 

[WheelEstate USA]

The older Coleman solar showers said (printed on them) to face the clear side to the sun. The new ones say to face the black side.
We find the clear side makes hot water faster.

 

[Wanderer]

Yesterday, September 28, I did my matte-black-painted one-gallon plastic water bottle experiment for a source of hot water without a stove or fire.

Great read!

 

[MrNoodly]

The irony of doing hot water this way is that we tend to crave hot water the most when there's the least sun -- cool, overcast, rainy...

 

[TrainChaser]

SternWake: Yes, I think that's too hot -- that's why I measured the temp of the tap water; at 115F, I have to add cold water when I shower. Half clear/half black -- that's a new idea! I'll try it.

Odyssey: I removed the label, shook the can for a minute, then sprayed the bottle. The instructions (Rustoleum for plastic) said to sand it, but the bottles are built like the corrugated metal roofing. I figured either it would work or it wouldn't. Never did a science fair. I learned all my stuff the hard way -- by mistakes.

MrNoodly: That is so true it seems stupid.

 

[Optimistic Paranoid]

Train Chaser, doesn't the SODIS method of purification utilize clear bottles? Is it the heat, or the solar Rays that actually purify the water in the SODIS method

It is specifically ultra-violet light that sterilizes the water.  Sub-boiling temperatures don't kill anything.

They actually make water purification systems that use an electric light bulb to sterilize the water.  Details here:

https://www.rvwaterfilterstore.com/ABUV.htm

 

[vanman2300]

Has anyone ever tried using one of those flat oil change containers? I always thought how it can sit atop a van without ever being noticed and that the flat profile would create a greater surface to volume ratio making the water heat up faster. I'm thinking about a set up where if a hose and sprayer were attached I could shower outside if I wanted to.

 

[highdesertranger]

sub boiling does in fact kill the nasty's, you do not have to boil water to make it safe to drink. pasteurization works too. http://solarcooking.wikia.com/wiki/Water_Pasteurization_Indicator . highdesertranger

 

[Optimistic Paranoid]

sub boiling does in fact kill the nasty's,  you do not have to boil water to make it safe to drink.  pasteurization works too.  http://solarcooking.wikia.com/wiki/Water_Pasteurization_Indicator .  highdesertranger

That's interesting.  We used to have cows, and my mother used to pasteurize the raw milk on the kitchen stove.  I don't know why it never occurred to me that you could pasteurize water.

However . . .

After doing a little research on it, it turns out that the temperature you need is 150 F.  The original poster here reported that she was only hitting 115 F with black painted bottles.  I'm sure that clear bottles don't even come close to that.  So I'm going to stick to my claim that any water purification that occurs to water in clear bottles left in the sun is due to ultra-violet radiation and not to pasteurization.

But I thank you for teaching me something new today.  You have answered a question I sometimes wondered about - boiling water at high altitudes where the water never hits 212 F.  I feel better now knowing that water is safe, too.

http://theweekendprepper.com/water/water-boiling-vs-pasteurization-whats-the-difference/

 

[highdesertranger]

actually I didn't know until recently myself. I was in the always boil camp. highdesertranger

 

[Ken in Anaheim]

....actually, the old-wives-tale about BOILING the water was just because most people in a purify-your-own-water situation didn't have a thermometer with them and most couldn't accurately gauge (guess) when the water reached the necessary 149 f., but everybody could see bubbles.

 

[highdesertranger]

that was true then Ken and still true to this day. everyone can tell when water is boiling. well almost everyone. highdesertranger

 

[SternWake]

Hey, black surfaces radiate more of their heat due to higher emissivity. So paint one side of the bottle black, then cover that black paint with white paint so the shady side of the bottle does not radiate as much heat to atmosphere.

Or instead of White paint, reflectix taped tightly with clear packing tape.

I threw my 5 gallon showerbag on top of my roof at I had to surf parked facing north. No way did it get near as hot as when resting on my black dashboard facing SW. Hot enough, but sometimes the steaming hot post surf rinse/ crevice wash, is really appreciated.

Really, I got to get the sunscreen off ASAP, which requires soap. Steamy hot water is hedonistic luxury.

 

[TrainChaser]

The SODIS method of pasturizing water uses the combination of both temperature and UV. That's why the container has to be clear, and not larger than 2 liters/1/2 gallon. As pointed out, the water also has to be clear. The SODIS people have suggested that you lay a piece of printed newspaper under the clear bottle, and if you can see the print clearly, the water is clear enough. You can help to clear the water of debris by filtering (even a t-shirt) and/or letting the debris settle and scooping the clear water off the top. Water that has clay that continues to color the water after the settling of larger debris is not a good choice for SODIS.

This post was just for heating water for washing people and dishes. While it should be clean, too, I was generally assuming that the original source would be clean. I hate bathing in cold water. Hate it, hate it, hate it. Except in summer after working.

I will continue to try some water-heating experiments, but at 60F with rain, the coming days don't sound encouraging.