OK, my head is going to explode. I need info about water pressure. Or really anything that may suck about my plan.
I want to collect rainwater from my gutters. I am going to buy a couple of 55 gal drums. I live in Portland Oregon, there is tax benifet and even a one time bonus of $52 on my water bill if I disconnect my downspouts from the sewer. I want to do this for environmental reasons, financial, and just for a fun science project around the house. Besides, I like anything that gets me further off the grid.
The problem is that I dont really water my plants much. I have planted my small yard with local plants that don’t need much care. I dont even have traditional grass, but envirolawn made up of small low growing grasses and flowers and clovers. Needs no water or mowing and is durable and easy and beautiful. Anyway. . .
I have to use the water for something so., I want to use it to flush my toilet. My idea is to put a barrel under each downspout. The bottoms of the barrels are even with the top of my only toilet. So the water pressure is at best 2 psi compared to the 40 or 50 psi of my city water. My toilet will not operate on that little pressure. So I need to increase it.
Here is where I get confused. It seems water pressure increases by elevation. This is why there are water towers. But it does not seem to be a function of volume at that elevation. So I must get the water up high. the peak of my roof is 15 feet above the top of my toilet. So I think I have to pump water up there. I figure I can hook up a small RULE pump designed for boat bilge pumps a small battery and a small solar panel. Put the float switch at the top of the bucket on my roof and the pump in the rain barrel. I do not want to place a 450 lb barrel of water up on the roof, so I was thinking of just a small 5 gal bucket on my rooftop. I figure that is enough for 3 flushes and the pump would trigger on after each flush to replenish.
My figuring is that it would deliver 6.5 psi (15 x .433). Does that make sense? Does the volume of water up high make any difference? IE do I get the same pressure from a 5 gal bucket 15 feet up as if I put a 55 gal drum 15 feet up?
How does all of this sound? I think that 6.5 psi will be enough, but I am not sure. Any thoughts?
The bottoms of the barrels are even with the top of my only toilet.
I think that is all you need to know. Toilets flush using gravity and water from the tank. As long as the barrel is above the toilet it will fill and flush. The tank won’t fill as quickly as with the higher pressure city water but you can remedy that with larger pipes and fittings between the barrel and tank.
When Hurricane Charley hit the west coast of FL a few years ago the city of Punta Gorda was without power and water for more than a week. My folks would use a 5-gallon bucket to scoop water from the pool to fill the toilet tank. Worked perfectly w/o pressure or power.
Your concept is good; your assumption about the static volume of the water is correct.
I do believe that the newer, low volume toilets need closer to 20psi to operate properly. You may be better served to use your energy source to operate a small pressure tank. Keep everything at ground level and you won’t have to lift the water, and you’ll also have water under pressure for other uses.
Till it just pisses down rain. At that point, you’ll be flushing your toilet every ten seconds to keep the barrels from overflowing.
It is indeed true that (real) toilets use gravity feed from the water in the tank. Also true you need only enough pressure to re-fill the tank. Shut the water supply to your toilet off and flush it to verify that you have a (real) toilet. If so, you’re good to go if you account for friction loss with your fittings and lead to the toilet supply.
Insure you have a backup source for the dry spells.
I do like the pressure tank idea anyway; you could use that water for anything then.
Yeah I have a new toilet. It does require some pressure. I read in one place that it would not work with on 4 psi. I was wondering how much I needed. I tested it by barely opening the valve at the toilet. It was just a trickle in and started to fill but then stopped too soon.
I have not looked at a pressure system. I want to keep it as simple as possible, and use as little energy as possible. Could I make a pressure system that runs on solar and still be pretty cheap? The tax breaks are $300 and the bonus is $54 so . . the total cost of the project has to be under $354. tanks cost $100 for 4 of them Pump and assc parts are about $100 SO I don’t have much more left to meet my goal. I will probably go over, but at least I can try.
Yeah, the volume of water doesn’t matter…to some degree. It’s the height of the water that will deliver the appropriate pressure. However, the volume of the water determines HOW LONG you can have that pressure. So, yes, if you have a pump refill your 5 gal bucket after every flush or so, then you should be able to make it work.
I, personally, am not sure how much psi you need to make a toilet work but your idea is sound. Like another poster said, as long as the water level of the bucket is greater than that of the toilet reservoir, then it should fill up.
NO WAY. I love my toilet. It is one of those low flow toilets but if flushes AWESOME!!! My old toilet was useless. This thing will suck down a small child if they are standing too near.
I guess its just the fill mechinism that I might have to replace. They can be pulled out and put one in with more sensitivity.
I just want this to be super simple to switch between rain water and city water. Ideally, when rain runs out, I just close the rain valve at the base of the toilet, and open the city valve. Any more steps than that, such as adjusting the flush mechanisms will not make my wife happy.
OK I dont understand how these pressure tanks work. They come precharged. Does that mean I dont have to hook anything else up to it? Does it need a pump of some sort?
is it as easy as hooking up an outlet from my rain barrels to this tank then wire the tank to electricity and then plumb to my toilet?
IF so , This seems like a good $70 spent,
t
EDIT BAH that seems to need a pump. Those seem expensive. ugh
I got to thinking about all of this. A pressure tank has to be charged with pressure from the source; i.e. if my well pump can only handle 40psi, I can only get 40psi into the pressure tank. So…
You need a small pump to fill your pressure tank. You can’t get pressure for ‘free’ (in the physics or economic sense) since you have to do work by pressurizing the water.
It doesn’t have to produce much flow but it will have to create pressure. you can also install a float switch operated solenoid 3-way valve to switch between rain and city water that switches to city when your barrel runs dry.
That pressure tank acts as an accumulator - here’s how it works. Let’s assume your toilet needs 1 gal/flush and it will “shut off” on low flow if it doesn’t get that water in less than 1 minute (this comes out to 1 gal/min, got it?). Now let’s assume that your pump only puts out 1 gal every 2 minutes - this would make your toilet “time out” because the water isn’t flowing to it quickly enough. This is where the pressure tank comes in, it pukes out its contents quicker than your pump can, but it can’t fill itself up.
Consequently, if you go with the pressure tank, you’re still going to need a pump. I doubt that a boat bilge pump can overcome the 28psi nitrogen bladder pre-charge in the accumulator, so that idea is out in my book. Also, most boat bilge pumps are rated between 200 - 1000 gallons/hour, so water flow is not going to be an issue.
When you look for boat style bilge pumps, make sure you derate their flow capacity for the elevation gain - which may cut the output by 50+%.
I dont know why they have rain water going into the sewer. I think its the norm for cities.
15 gal per day is about what I think is right in terms of savings. But hey, that is 5,500 gals per year. The funny thing is, our city water, comes from rain.
So I guess I save a few things. Rain falls from the sky, gets stored in our reservoirs, gets treated with chemicals and energy, gets pumped through our infrastructure to my house. I then pay for it, and immediately flush it down the toilet and actually pay sewer costs to get rid of it. All the while, I am running rainwater down the same sewer that contributes to over filled sewers and eventually CSOs (combined sewer overflows) that put raw untreated sewage into our beautiful river. It all just seems silly to me. So I am doing my part to remedy this even in a little micro sense and hopefully save money and add self sufficiency.
It still remains a goal to use mostly reclaimed materials to build the whole system.
I think the next step is to just hook a length of hose to my toilet. Then the other end to a bucket on the roof with a couple of gallons in it. They give it a try.
Oh, I like the selenoid idea. I think I might have to incorporate that. I was just planning on putting a t valve in at the toilet connection.
I think I will have plenty of rainfall to use. I am not sure of my math, but I figure a 30 by 30 foot roof equals 129,000 square inches. We get 36 inches of rain per year, so I multiply 36 x 129000 and get 4.5 million cubic inches of water, then divide by 231 to get about 20,000 gals of water running off the roof each year. Is my math correct? I would only use about 25% of that to flush toilets. The rest goes down the sewer I guess. There will be some transfer losses too. . .
Oh I had not thought of how powerful the pump would have to be to lift the water up there. I was looking at the RULE 360. it does 360 gal per minute, I dont need that much. Do you think it will lift water even at a slow rate up 20 feet?
It might not work…most bilge pumps only have to pump the water up 2 - 4’ to get to a exit on the side of the boat that is above the water line.
Try googlin’ “pumping water uphill”.
You only need to lift water x feet. How many psi would that be (you can answer your own question). give yourself an extra 15% for fudge and friction. (we educated farmers call this the spluge factor, engineers use it also, but charge a lot more)
GPM is irrelevant and a function of convenience. You need only replace what you use at the speed you use.
Motor control is a different story.
You’ll figger it out, its good for you to think about new things
I think the hard (expensive) part of your project is going to be plumbing a 2nd (rainwater) line to all of your toilets.
I think ideally you would put a pressure tank in the basement with a pump to pump water from your collection barrels. Of course, you would need some kind of cutoff valve at each barrel to keep it from pumping dry, and some system/circuit to shut off the pump when all the barrels were empty.