# Recycle water from project **URL:** \ **Category:** Factual Questions\ **Created:** [November 13, 2011, 12:19pm UTC](https://boards.straightdope.com/t/recycle-water-from-project/602787 "2011-11-13T12:19:54Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![nando88](https://avatars.discourse-cdn.com/v4/letter/n/439d5e/32.png) [@nando88](https://boards.straightdope.com/u/nando88)\ **Post date:** [November 13, 2011, 12:19pm UTC](https://boards.straightdope.com/t/recycle-water-from-project/602787/1 "2011-11-13T12:19:54Z")
I’m planning to do this project: [http://mrwilliams.hubpages.com/hub/How-](http://mrwilliams.hubpages.com/hub/How-) … lectricity and I want to know if I can use soil as a filter to recycle the water I would be using in this project? If I use soil as a filter, would the water still be salt water or just pure water? Would I be able to use this water (recycled water) to irrigate plants, and what PH should it have in order for me to use it to irrigate plants? How can I change the PH in this recycled water? If I use soil as a filter, would I need to change the soil from time to time or is it not necessary? I need to add chlorine to the water to make this project, so is it possible to remove the chlorine in some way, like if I use soil as a filter, would it remove the chlorine from the water? Thanks in advance! ---
**Author:** ![ZenBeam](https://avatars.discourse-cdn.com/v4/letter/z/3ab097/32.png) [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)\ **Post date:** [November 13, 2011, 1:46pm UTC](https://boards.straightdope.com/t/recycle-water-from-project/602787/2 "2011-11-13T13:46:55Z")
Link doesn’t work. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 14, 2011, 1:23am UTC](https://boards.straightdope.com/t/recycle-water-from-project/602787/3 "2011-11-14T01:23:01Z")
You can’t desalinate water just by filtering it, except under extreme circumstances: You need a semipermeable membrane that will let water molecules through but not salt ions (dirt does not qualify for this-- You’d need something very precisely made for this exact purpose), and then you also need to put very high pressure on the salty side of that membrane. The only desalination method that can be done on any scale in a home project is evaporation and re-condensation (though this is almost guaranteed not to be economical-- You’d be better off just getting more water from the tap). And any desalination method at all will necessarily involve a significant amount of energy input. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [November 14, 2011, 4:00am UTC](https://boards.straightdope.com/t/recycle-water-from-project/602787/4 "2011-11-14T04:00:08Z")
I’m guessing this is the link the OP intended: [http://mrwilliams.hubpages.com/hub/How-to-make-electricity](http://mrwilliams.hubpages.com/hub/How-to-make-electricity) I wouldn’t try those experiments. The author of those clearly has no idea what he is doing and is repeating bad information from internet pranks. The first “experiment” mixes vinegar and bleach, which is going to release chlorine gas. Avoid this one just because of the health risk. Chlorine gas is poisonous. The second “experiment” is based on a fake youtube video and it’s not going to do anything productive. You won’t generate electricity. It’s been a while since I’ve seen the youtube video but IIRC it was fairly obvious to me that the hoaxer was flipping a switch under the table. The third “experiment” is the only one that will actually do anything useful. Two dissimilar metals in any kind of acid makes an electrical cell. The bigger the pieces of metal, the more current you’ll get, but these types of batteries do tend to be fairly weak. Lemons work fairly well. Potatoes aren’t an acidic fruit but they work fairly well also. A quick and easy lemon battery is to use a penny (copper) and a dime (zinc) for the electrodes. A galvanized roofing nail is also zinc and is a bit easier to shove into the lemon. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 14, 2011, 7:03am UTC](https://boards.straightdope.com/t/recycle-water-from-project/602787/5 "2011-11-14T07:03:25Z")
OK, now that we have the link, I can say that that site is full of hooey. Right off the bat: > [@](#): > > Cheap electricity can be achieved if you learn how to make your own electricity because you won’t be using the home electricity. Therefore, you will end up with cheap electricity. You might end up paying less on your electric bills, but you’ll end up paying a lot more than that for whatever metals you use to make the batteries. The “Therefore, you will end up with cheap electricity” is a complete non sequitur. If these methods really were cheaper than what the utility company charges, then they’d make power plants with lemons and coins, instead of coal burners and turbines. And of course, the candle one is a complete hoax, as **engineer\_comp\_geek** already pointed out, and not even a very good one. You can tell because there’s nothing in the setup to distinguish one terminal from the other: How is the candle supposed to know which end to make the positive terminal, and which the negative?