Baffling rainwater catchment tank problem

[JThomas]

Early in January 2022 I had a new 14000 gallon catchment tank installed on my property in Hawaii. When the installation was complete, I had 6000 gallons put in the tank. Heavy rainfall added enough added enough to bring it up to about 12000 gallons, enough to last 1200 days, if I do no irrigation (ten gallons usage per day, max). But no. by the middle of the month, we had no water available. The tank was found to be empty down to where the foot valve could not pick up water (6 inches). Two possibilities presented themselves: a leak in the tank liner or a leak in a pressure line. We put another 6000 gallons in the tank to check these out. With the pump on, we found no pressure line leaks. Plus, there was normal pressure at kitchen faucets, which there would not be if there was a bad pressure line leak.

With the pump turned off, the water level in the tank dropped from just over 30 inches down to about 18 inches, a rate of about 2000 gallons per 24 hour day. There it remained. The liner was examined at that water line by three different people and no damage was found. There was no sign of that much water leakage anywhere on the property. The ground at the perimeter of the tank remained dry at all times.

I'm hoping to find someone who has encountered a similar situation and who has found a solution.

 

[Twowaxhack]

Sounds like your tank has a leak.

That’s the only other way for water to leave the tank if the pump is not running.

 

[Twowaxhack]

You may have an irrigation head siphoning the tank with the pump off.

 

[RS]

Loosing that much water that quickly should be obvious! I agree it might be siphoning into the irrigation system. Do you have any isolation valves so you can troubleshoot the system? If you don't you may need to install some, it can't be cheap having that much water delivered!

 

[BlueSkyHigh]

Loosing that much water that quickly should be obvious! I agree it might be siphoning into the irrigation system. Do you have any isolation valves so you can troubleshoot the system? If you don't you may need to install some, it can't be cheap having that much water delivered!

And speaking of being expensive, this brings to mind my experience as a member of the US Navy stationed at NAS Bermuda which is now decommissioned. A new Lt.JG supply officer wanted to save a few buck and look good for the base's C.O. so he purchased some less expensive paint with which to paint the base's main water catchment system. The young Lt. only realized that he purchased lead-based paint AFTER the catchment had been refinished. It cost a boat load of money to remove the lead-based paint from the system plus the cost of shipping in the replacement drinking water for the next couple of months.

It does beg the question, however, of that what do you do to mitigate or eliminate the contaminants that rain water, bird "lime", etc, that gets into the system?

Good luck in finding the cause of your water loss!

 

[JThomas]

Sounds like your tank has a leak.

That’s the only other way for water to leave the tank if the pump is not running.

Thanks for the reply. The first time I lost water (aprox. 12000 gallons)the water level went down to the bottom of the foot valve (6 inches or so from the bottom). This would suggest a liner leak at that level since we don't use very much water. More recently I added 4000 gallons to troubleshoot the system. Pump off. The water level dropped to the 18" level and stayed there, suggesting a leak at that level. If there is a leak at the 6" level, why did it stop at the higher level? ISee why it doesn't seem like a simple problem?

 

[JThomas]

Loosing that much water that quickly should be obvious! I agree it might be siphoning into the irrigation system. Do you have any isolation valves so you can troubleshoot the system? If you don't you may need to install some, it can't be cheap having that much water delivered!

Thanks for the reply. I don't have an irrigation system yet. Just household usage of maybe 20 gallons per day. No running toilets and no pressure line leaks. no signs of a big (or small) leak anywhere. The soil around the perimeter of the tank is dry, aside from what might be expected from recent rain. 2000 gallons a day is a lot of water to just lose.

 

[JThomas]

And speaking of being expensive, this brings to mind my experience as a member of the US Navy stationed at NAS Bermuda which is now decommissioned. A new Lt.JG supply officer wanted to save a few buck and look good for the base's C.O. so he purchased some less expensive paint with which to paint the base's main water catchment system. The young Lt. only realized that he purchased lead-based paint AFTER the catchment had been refinished. It cost a boat load of money to remove the lead-based paint from the system plus the cost of shipping in the replacement drinking water for the next couple of months.

It does beg the question, however, of that what do you do to mitigate or eliminate the contaminants that rain water, bird "lime", etc, that gets into the system?

Good luck in finding the cause of your water loss!

Thanks for the reply. It costs $220 to have 6000 gallons of water delivered. if rainfall is good, that can fulfill a homeowner's needs. Catchment water is not usually used for drinking, although you can install a triple filter system plus a UV filter and get very good water. Some add chlorine periodically.

 

[Twowaxhack]

You have a leak somewhere. You need to find it. It’s really that simple unless you’re considering there’s magic at play.

You need an isolation valve so you can determine if it’s the tank leaking or the piping connected to the tank leaking.

You could also install a water meter at the outlet to check for a leak. Water meters have a small leak indicator.

 

[wpns]

Depending on the level of your cistern compared to the house, even with the pump off you may have enough static pressure that any leak might siphon water out of the tank. Also, some appliances like clothes washers use the pressure of the water to keep their solenoid valves closed, so if the water pressure drops low enough they can pop open. [My clothes washer leaked in this manner for months all over the downstairs while the house was closed up for hurricane season!]. I'd suspect that the reason you aren't seeing any leaks is that the water is all going out into your septic system. Get a plastic water meter with a 0.1 gallon per pulse output and monitor your usage, I think you'll be surprised.

 

[wpns]

ten gallons usage per day, max

I'm not sure where you get that number. The "North American Standard" is 100 gallons per person per day, we use (SWAG) 75GPD per person, I've seen claims of 25GPD/person, but 10GPD is barely enough for drinking and flushing, much less bathing and laundry and cooking/cleaning.

 

[wpns]

Catchment water is not usually used for drinking, although you can install a triple filter system plus a UV filter and get very good water. Some add chlorine periodically.

We use an Ozone For Tanks system from Home - TRIPLE O which works really well, every gallon is 'municipal quality' without the chlorine levels bouncing all over like they do when dosing manually, and then I don't have to worry about where my water comes from for making coffee or brushing my teeth or washing vegetables, or showering, or ....

 

[Twowaxhack]

We use an Ozone For Tanks system from Home - TRIPLE O which works really well, every gallon is 'municipal quality' without the chlorine levels bouncing all over like they do when dosing manually, and then I don't have to worry about where my water comes from for making coffee or brushing my teeth or washing vegetables, or showering, or ....

I visited that website and closed it when I read that “ you can drink out of your garden hose “ and they show a little boy drinking from the hose.

That’s bad business and its false advertising. Drinking from a water hose should be avoided.

 

[wpns]

I visited that website and closed it when I read that “ you can drink out of your garden hose “ and they show a little boy drinking from the hose.

That’s bad business and its false advertising. Drinking from a water hose should be avoided.

Well, sure, you shouldn't drink from a garden hose unless it's rated for potable water (who knew lead was a thing?), and I wouldn't drink from mine because I also have a UV light which converts the ozone back to oxygen before going into the house, but their point is that it's all potable water. Been using those ozone systems for decades now, and the only thing I've noticed is that folks don't get sick any more, and kids don't get ear infections more more.

 

[BlueSkyHigh]

I visited that website and closed it when I read that “ you can drink out of your garden hose “ and they show a little boy drinking from the hose.

That’s bad business and its false advertising. Drinking from a water hose should be avoided.

I still eat snow ice cream and I grew up during the era of above ground nuclear testing when radioactive fallout in your snow ice cream was considered risky business.

 

[Twowaxhack]

I still eat snow ice cream and I grew up during the era of above ground nuclear testing when radioactive fallout in your snow ice cream was considered risky business.

Cool story bro

 

[JThomas]

You have a leak somewhere. You need to find it. It’s really that simple unless you’re considering there’s magic at play.

You need an isolation valve so you can determine if it’s the tank leaking or the piping connected to the tank leaking.

You could also install a water meter at the outlet to check for a leak. Water meters have a small leak indicator.

Sounds like your tank has a leak.

That’s the only other way for water to leave the tank if the pump is not running.

Thanks for your response. Well, there are the menehune, or Hawaiian little people, who are known for mischief. Don't laugh. fifty-odd showed up on a 19th century census.

I still think a liner leak is the answer, but the first two leaks dropped the water level to six inches, while the next leak dropped it to about 20 inches, where it remains. What happened to the lower leak?

 

[Twowaxhack]

Thanks for your response. Well, there are the menehune, or Hawaiian little people, who are known for mischief. Don't laugh. fifty-odd showed up on a 19th century census.

I still think a liner leak is the answer, but the first two leaks dropped the water level to six inches, while the next leak dropped it to about 20 inches, where it remains. What happened to the lower leak?

Maybe you have two leaks now......a lower leak developed after the first one.

Just guessing

 

[JThomas]

I'm not sure where you get that number. The "North American Standard" is 100 gallons per person per day, we use (SWAG) 75GPD per person, I've seen claims of 25GPD/person, but 10GPD is barely enough for drinking and flushing, much less bathing and laundry and cooking/cleaning.

We have an outhouse (the most environmentally friendly system, by the way, at least in much of hawaii). low volume shower heads.I can't imagine using anywhere near 100 gallons a day Also, drinking and cooking uses water we haul in
from a free water source.

 

[JThomas]

Maybe you have two leaks now......a lower leak developed after the first one.

Just guessing

thanks for the reply

It would have be the opposite. The lower leak would have to have gone away, leaving the job to an upper leak.