Water filtration and safety - rainwater cistern

[Sid Post]

It looks I may have bartered for a rainwater catchment tank. Thinking I will want to have this potentially for drinking water or at least showers and similar uses, I asked around about water safety.

A lot of people are telling me I need a chlorine system. Others say just UV light. What is reasonable? I don't need reverse osmosis purity levels but, also don't want to make myself or anyone else sick. I'm initially assuming dust from the metal roof will settle in the tank so, I don't need filtration specifically for 'debris' and will screen my gutters.

TIA,
Sid

 

[Reach4]

For UV, you need to filter out particles that could shade bacteria from UV. Five micron is sometimes recommended.
https://rainwaterharvesting.tamu.edu/after-storage-treatment/ says

An important point to keep in mind is that UV lights are most effective when the water is clear. Any sediment in the water can block the pathogens from the light. This is why have the filtration BEFORE the UV light is so critical.​

http://www.shl.uiowa.edu/env/privatewell/homewater.pdf says

Particles in the water greater than about 5 microns in size may reduce the UV’s disinfection ability by shielding bacteria from the UV light.​

 

[Sponsor]

 

[Sid Post]

Thanks Reach4! I'm looking at an "Ag filter" with a 5-micron filter size so, it looks like I was on the right track.

 

[Reach4]

Thanks Reach4! I'm looking at an "Ag filter" with a 5-micron filter size so, it looks like I was on the right track.

Is that similar to a sand filter? http://www.clackcorp.com/downloads/ion_exchange_resin_and_filter_media/filter-ag_2351.pdf If so, I think I would follow it with a cartridge filter. If the cartridge catches nothing, it will not need changing often.

 

[GTOwagon]

So no chlorine then? What about bird poop and dead insects and other matter in there? H2O2?

 

[Sid Post]

Yes, Filter-Ag Plus Sediment Filter System.

It looks like it is best to follow it up with a UV light & filter system or a chlorinator. I'm still going through the TAMU.edu links and article though.

 

[Sid Post]

So no chlorine then? What about bird poop and dead insects and other matter in there? H2O2?

A diverter pipe will get the vast majority of that before it hits the tank. I will also use those bird wire mats to reduce the fecal deposits.

For biological safety probably UV light but, Chlorine is a possibility too.

 

[Valveman]

Going to move this to the softener forum where more eyes will see it.

 

[ditttohead]

Unless you are willing to do this correctly... I would not recommend using this water for drinking or "potable" use. How much rain do you actually get and is it really worth the cost? Do you do enough irrigation to use this water exclusively for that?

In general, a surface supply should have a redundant sanitization method. There are a multitude of ways to do this. Chlorine is the obvious choice. You should follow that with UV or you could also consider some form of properly rated filtration method.

Rain water tends to be very low tds/pH so correction can also be needed to protect your plumbing. A simple polyphosphate injection, soda ash, calcite or other form may be needed.

If you use if for irrigation... a simple filter will suffice so long as you don't drink from the sprinklers.

 

[Sid Post]

Going to move this to the softener forum where more eyes will see it.

Thanks!

 

[Sid Post]

Unless you are willing to do this correctly... I would not recommend using this water for drinking or "potable" use. How much rain do you actually get and is it really worth the cost? Do you do enough irrigation to use this water exclusively for that?

In general, a surface supply should have a redundant sanitization method. There are a multitude of ways to do this. Chlorine is the obvious choice. You should follow that with UV or you could also consider some form of properly rated filtration method.

Rain water tends to be very low tds/pH so correction can also be needed to protect your plumbing. A simple polyphosphate injection, soda ash, calcite or other form may be needed.

If you use if for irrigation... a simple filter will suffice so long as you don't drink from the sprinklers.

In Tucson, Arizona I used reclaimed 'grey' water from the city. For a residential use like mine at the time, the amount of paperwork and bureaucracy involved was enormous. I had to protect my Xeriscape drip irrigation from people's pets and wild animals too. The annual certification required is not something I would do today.

Where I live now, I have 40'x60' equipment shed I plan on using. After looking up how many gallons I get from 1000ft*ft of 'catchment', a 5,000-gallon tank may be a bit undersized.

I have two other areas a bit smaller and one a lot larger for possible 'catchment' too. I'm on 40 acres and not in a backyard so, during a typical 'dry' Summer I'm pretty sure I would drain it dry. If nothing else, I would use it in my front pond instead of well water.

After more thought about sanitization, I'm leaning real hard towards Chlorine. For Ph, I have very little concern adding stuff like I do now to fish ponds and tanks (>750-gallon industrial setups on solar power). In retrospect, for household water use, branching off my well to drive water with a pump off 330-gallon IBC tanks from my rainwater tank would suffice nicely for low well outputs if that becomes an issue during a dry spell.

A bit of chlorine and some other chemistry for Ph in an IBC plus what the well house currently does should protect both my health and my plumbing. I'm still kicking around my options though so, other thoughts and recommendations are appreciated and welcome!

 

[GTOwagon]

I feel if you have a pond that holds water, divert it here and pump from it to a 120 gallon contact tank with chlorine injection, and your necessary soda ash or whatever to raise then put it through a backflush Carbon filter... Then use it for toilets, your laundry, car washing, pet bath, etc. ...watering your lawn can come straight from the pond I would think.

So instead of a cistern use the pond to hold the water, pump what you need, treat what you need. Use the money you were going to spend on a huge tank to invest in the treatment system and the pump system for the irrigation.

I invite being told I don't know what I am talking about if someone with experience doing this has a better plan.

 

[Reach4]

So instead of a cistern use the pond to hold the water, pump what you need, treat what you need.

The rain water will start a lot cleaner and purer than pond water.

 

[GTOwagon]

The rain water will start a lot cleaner and purer than pond water.

That is true. But lots of people draw their water from a lake or pond. I figure chlorine, contact tank, ag filter, Carbon filter, done. But for simply sprinklering the lawn, a pump and a Lakos or something straight to a hose system.

I did see he was bartering for a tank. I was thinking and forgot he wasn't buying a tank. Those tanks are big money. But it seems rigging the water to go through a separator, or whatever then get it to the tank is a bit of a PITA vs. sending it via 6" Olin pipe underground from downspouts to the pond.

 

[GTOwagon]

Is the well unproductive or low volume? Does it go dry?

 

[Sid Post]

I feel if you have a pond that holds water, divert it here and pump from it to a 120 gallon contact tank with chlorine injection, and your necessary soda ash or whatever to raise then put it through a backflush Carbon filter... Then use it for toilets, your laundry, car washing, pet bath, etc. ...watering your lawn can come straight from the pond I would think.

So instead of a cistern use the pond to hold the water, pump what you need, treat what you need. Use the money you were going to spend on a huge tank to invest in the treatment system and the pump system for the irrigation.

I invite being told I don't know what I am talking about if someone with experience doing this has a better plan.

I don't water my 'lawn'. I'm in East Texas over 1000' from the county road behind trees and a hill so, the only one that sees my 'lawn' are myself, feral hogs, some cattle, and a dog.

The 'front scenic pond' is not a water source for me and will never be so. If I don't put water into it over the summer, it gets really low to the point of having a FISH KILL. That's why having something other than my well is attractive during a HOT DRY SUMMER. And yes, at some point I will 'fix' the front pond so it waters cattle better without making it a muddy mess, has a better dock for grandkids to fish off and, has some clay added to it to hold water better.

My house is DRY right now so, I'm sure this 'schews' my thinking and biases me a good bit. This is why I'm asking questions and thinking out loud. I'm sure there are many ways to achieve what I'm asking and the optimal way depends on where you live to a certain degree (my experiences in rural Oklahoma versus Tucson, Arizona are radically different).

I'm also not a water engineer so, I don't want to be 'taken for a ride' by some questionable people who are pushing systems that are $6K to $20K for a farmhouse 'potable' water system. For ~$20K, I'd drill a larger (more than 4") hole with a 5HP pump with a goal of 37GPM like my friends well down the road a mile or so.

 

[Sid Post]

The rain water will start a lot cleaner and purer than pond water.

And it won't have algae and other growth that has to be dealt with. Tilapia and Geese are good for algae and pond weeds but, Geese especially are nasty creatures.

 

[Sid Post]

That is true. But lots of people draw their water from a lake or pond. I figure chlorine, contact tank, ag filter, Carbon filter, done. But for simply sprinklering the lawn, a pump and a Lakos or something straight to a hose system.

I did see he was bartering for a tank. I was thinking and forgot he wasn't buying a tank. Those tanks are big money. But it seems rigging the water to go through a separator, or whatever then get it to the tank is a bit of a PITA vs. sending it via 6" Olin pipe underground from downspouts to the pond.

The shed 'catchment' right now drains into the pond in question. The problem is the rain goes over the spillway in Spring and Summer's are dry. Fall and Winter are generally not an issue either with natural rainfall. However, having a large store of rainwater during a dry Summer will help carry me through the worst of Summer without tapping my well.

Having an IBC of rainwater available if I have a well problem at the house is a nicety for me as I get older as I like flush toilets and not having to fix a well that is down RIGHT NOW! Optimal decisions are normally not made in a panic or crises and that seems to be what happens when water goes out Thanksgiving morning or Chrismas Eve. Murphy's law says water only goes out when I have a really big public event, never when it's just me working on the farm.

 

[Sid Post]

Is the well unproductive or low volume? Does it go dry?

The first well went dry long ago. The second well was sulfur and iron (too shallow a well by the previous owner trying to save a buck). The current well is ~560' down (based on sketchy info) with a 1HP well pump doing ~5GPM and is in the very top of a good aquifer with very light iron and no sulfur. I was overusing it on a Garden and fish tanks when it started acting up so, last fall I quit using it. Pump wiring was 'daisy chained' in the ground from the house, the maintenance shed, to a gazebo to a breaker box that went to a barn and the well pump. Is a 50A breaker for a 1HP well pump the right one? At least the pole light was only on a 20A breaker.

With a major line break on "city water" while in Oklahoma, I came back to a $2000 water bill in 4 days. With the rains we have, there is no way to spot the break in the front pasture since I don't have a 'wet spot' or 'water fountain' so, city water is shut off. I tried to start my well for some water for the house on a short-term basis to discover my control box among other things was dead. The well pump is still good with a test with a temporary control box.