MCL for Calcium and Sodium

[Stonkey]

I'm working on getting a water treatment system put in at the facility where I work. I got a water test done, and I know that the water is very hard. The three main substances that cause hardness are iron, calcium, and magnesium. It was easy enough to get the MCL (maximum contaminate level, a.k.a. recommended maximum level) for iron, but the state doesn't have an MCL for magnesium or calcium.

I know that the water softener should remove all three, but I'd still like to have some recommended levels to present to the board of trustees. Anyone have some rule of thumb levels for calcium and magnesium?

 

[speedbump]

I've heard some salesmen say that 2 grains is hard. I had 7 grain water at one home years ago and the water was fantastic. Lathered very quickly and had no iron. I would say that anything over 7 grains is hard though. Average in my area is 15 grains, but I have seen it as high as 42 grains. 1 grain is 17 ppm or mg/l.

I never liked to use a softener for iron. I never had any luck with getting all the iron with one and the iron tends to shorten the softeners life. They do make iron filters and I contend that they make them for a very good reason.

Iron will stain if you have only .25 ppm.

 

[Stonkey]

Thanks for the response.

The calcium is 47.3 mg/L, and the magnesium is 12.4 mg/L (the iron is 0.452 mg/L).

So that means I have ~2.75 grains of calcium, and a little less than 1 grain of magnesium. That doesn't quite add up because the test says I have 9.88 total hardness.

I'll have to look into an iron filter. That's the substance we really seem to have the problem with. Unfortunately, I've had several (4) plumbers over to look at the system, and none of them really seemed to know what to do to treat the water. So I'm try to do some research on my own, and I hope you don't mind if I ask a couple more questions.

One problem that the water test does not show is a sand problem. I don't know if the well pump is sitting to low or what, but we get lots of sand in the water or what. Would an iron filter remove the sand just by virtue of actually running the water though something, or would I need another device?

Do you have any recommendations on good models of iron filters? The building has about 20 fixtures (very rarely is everything in use at the same time though), and it runs at 70-80 gallons per minute.

 

[speedbump]

70 to 80 gpm is a bunch of flow. I thought we were talking residential. There are units that will take care of it, but they will be large. I also think when they said you had 9 grains, they were adding in the iron somehow. There are different trains of thought on that one.

I would go with an iron filter only, since your water is practically soft already. Your not irrigating with the water we are referring to are you?

 

[Stonkey]

Yeah, it's a commercial building (a church actually). I guess I should have mentioned that right off. I sort of implied that with "facility where I work", but I didn't actually say it. Haha. Unfortunately that makes everything more annoying and expensive.

We don't regularly irrigate. I'll have to ask if the landscapers ever do spot watering or something.

 

[speedbump]

Even with the 70 to 80 gpm, does that mean that much flow is a common thing, or is it more like half that on Sundays and special events? I'm trying to come up with a nominal flow rate so I can size up a unit that would work for you.

 

[Stonkey]

Truthfully, I'm not really sure how to evaluate it. As far as I know, we have never had any water flow problems.

We also have a pre-school that meets in the building during the week. But they only have one toilet/sink on their side of the building. Even during special events, it is very rare that all the bathrooms would be in use while people are watching dishes in the kitchen or anything.

Any thoughts on a good way to test the water flow?

 

[speedbump]

Only way I know to do a flow test would be by installing a meter that reads in gallons and get a weekly average. It could also be watched between the hours of an event where there are a lot of people present. Then come up with an average and a peak flow amount.

 

[Stonkey]

I was afraid that was the only way. I'm not sure that that is worth the trouble though.

I'll probably just operate under the 70-80 gallons per minute assumption. I'm assuming that once you break into the commercial grade treatment systems, you are already making the big price jump. Is it also a big price jump from 40-50 gpm systems to ones that can handle 70-80 gpm? I hope not, but I don't price this stuff out very often, so I'm unfamiliar.

I guess I shouldn't be so hopeful though. With these things, you always pay (exponentially) for every gpm.

 

[Stonkey]

For the sake of completeness, let me say where I got the estimation of gpm. There is a plumber in the church that does a lot of work with the boiler system. He is the one who told me we'd have 70-80 gpm, but he did so when he was telling me to be careful when working with one of the urinals. So he might have been exaggerating to make his point.

Here's the list of fixtures:
Toilets: 7
Urinals: 3
Sinks: 7
Outside spigot: 1
Dishwasher: 1
Clothes washer: 1

I don't have the formula/software to calculate the gpm. Perhaps my understanding is way too high. That's really something that I should look into before I start asking for help. Haha.

 

[phishfood]

Is this system supplied by a well, or through a public water system?

If a public water system, they should have records that will give you a good average.

 

[speedbump]

[QUOTE
Here's the list of fixtures:
Toilets: 7
Urinals: 3
Sinks: 7
Outside spigot: 1
Dishwasher: 1
Clothes washer: 1
[/QUOTE]

I agree with Phishfood. If it's city, there has to be a record of the monthly usage. If it's a well, maybe you can find the info on the pump and well. Those two things would tell us a lot.

I'm no Engineer, but roughly I come up with less than 45 gpm if all the above were used at the same time. And in my experience, you could use half that number and be pretty safe. So now, your getting into a unit larger than a domestic one, but not getting into the expensive ones.

One more thing that would help is the size of the supply pipe feeding the Church.

 

[Stonkey]

It is a private well system, and there are no meters on the well itself (I don't know about the pump, which is ??? feet down in the ground). I had a Culligan guy come out, and he estimated 56 gmp. So, we are definitely getting out of the range I thought we were in (it's possible that he over-estimated too, to sell us a larger unit).

The line coming into the building is 1 and 1/4".

 

[speedbump]

Since I have to believe this building was build by code, and it's got an 1-1/4" mainline; and my friction loss chart stops listing the loss figures at 45 gpm, I'm thinking your right about the neighborhood Culligan Man. I'm thinking more in the neighborhood of 35 gpm max. If your interested, I can get you a price Monday as my supplier is closed today. You certainly wouldn't want to go too big with a softener because as they get bigger, they require more water to backwash. If your well doesn't supply that much, it doesn't backwash properly and now you have another problem to contend with.

 

[Stonkey]

Sounds good to me. I'd appreciate it if you could toss me the price and make/model for a unit that would suit the function. The board of trustees doesn't meet till early next month though, so it's not a terrible rush. I'm hoping to write something up this Friday.

 

[speedbump]

For a unit with a 1-1/2"Fleck 2850 head, 21" X 62" tank which is a 7 cubic foot unit with a Peak flow of 48 gpm and a service flow of 36 gpm, brine tank etc. $2036.00 plus shipping.

 

[Stonkey]

Thanks man! Looks good. I'll definitely print some stuff out on it and present it to the board. We'll see what happens.