Hard water, electric water heaters (resistance and heat pump), and dirty dishes

I've been cleaning mineral sediment our of our electrical (resistance) water heaters for years. Apparently, the minerals in our hard well water collect on the electrical heating elements, break off as the elements thermally expand, and then collect on the bottom of the tank. The pieces are even shaped the same diameter as the elements.

We bought a new energy and water efficient (and made in the USA) Bosch dishwasher about 2 years ago and have been really happy with it.

So I went to clean out our water heater around Christmas and found I couldn't remove the lower heating element without destroying it. I usually remove the drain valve and the heating element for the cleaning process. The unit was 20+ years old and I've been looking for an excuse to install a heat pump water heater so we bought one and took advantage of a sale at Lowe's and a 30% federal tax credit. We bought the GE GeoSpring HP water heater and one of the things I liked about it was that the heating (condenser) coil is wrapped around the metal tank externally so there was no contact with the water. Insulation covers the coil. The GeoSpring works great and the payoff period should be short based on our decreased electrical load (and "free" basement de-humidification).

Then we start noticing that our dishwasher doesn't seem to be cleaning the dishes. There's a nasty film growing on them and we think the dishwasher is to blame.

Then we realized that our problems started shortly after installing the new water heater. We suspect water temperature. No, that wasn't it. The water in the dishwasher is plenty hot and has its own inline water heater anyway. We tried different detergents with no luck either.

Then the realization hits -- our old water heater was basically acting as a water softener; duh right? I'd realized that before but I never connected hard water with dirty looking dishes. So we add some special sauce to the dishwasher every so often and all is well, the dishes come out sparkling, our power bill is less, and I'm not cleaning the gunk out of my water heaters every year.

Just thought I'd post in case anyone else has similar experiences.

PS: We run our the Geospring in the HP only mode. If we were to run it in hybrid mode where the electrical heating elements are used when loading is heavy, we'd probably still have sediment build up in the tank.

woodgeek said:

'They' have also been reformulating automatic dishwashing detergent over the last few years, removing TSP in different geographical areas nationwide. I noticed a similar problem in my dishwasher a few years ago, without the change in heater. What product do you add?

Click to expand...

"Lemi Shine" We got it at Kroger.

NATE379 said:

Have you had your water tested?

I went about a year with hard water in a brand new house. It nearly ruined teh shower surrounds, toilets, water heater, boiler, dishwasher, clothes washer (and all teh clothes!). Installed a softener and much better now.

Click to expand...

Yeah and we know its hard. We prefer to deal with the scale rather than deal with the adverse effects of softening water (more salt in the environment, bad taste, power usage, cost).

NATE379 said:

The salt is minimal. Have used about 250lbs of it over the last year. That equals about a 40lb bag every 2 months.

There is no taste difference I have ever noticed, if anything it's better.

Electric is very minimal. I would guess maybe $5 a year to run it. All mine uses for power is to run a clock and little valve. I bet it uses less juice than an alarm clock.

In the end, far less expensive to have a softener than dealing with hard water issues.

If your water is not too hard it might be ok to get by, but it doesn't' sound like it. Mine was 35gpg on one test and 40gpg on the other, which I was told is very hard.

Keep in mind ANYTHING using water is getting ruined. Toilets, shower, sinks, washer, dishwasher, water heater, boiler, fridge, even the piping, drains and septic! Oh and your skin and clothes too. My clothes were getting to the point that there was so much minerals in them it was like I had applied a very heavy starch. My work uniforms which usually last 2-3 years where only making it 6-8 months before they were really faded.

Click to expand...

You've convinced me that I need to test my water. I'm wondering just how hard it is and what the specific hardness constituents are (Calcium versus Magnesium).

The house is 20+ years old and we've had zero problems with hard water issues other than the hot water heaters, scale on chrome bath plumbing fixtures, and scummy dishes. We even use the water in our ground source heat pump and I've inspected the copper heat exchangers and found little or no impact from scaling. I've also inspected plumbing in other places like solenoid valves on washers and found no issues. During numerous plumbing modifications I've seen no impact to piping I've removed.

Its been shown that some hardness in copper piping soldered with lead alloys can be beneficial because the scale layer prevents the lead from entering the water. Our house is old enough that I'm more concerned with the lead than the hardness. Numerous studies also show that softened water frequently contains salt and is not good for folks with hypertension (like me). High salt concentrations in septic systems has also shown to be detrimental to the biological degradation occurring there. We lived with naturally soft water in Texas and I always hated how soap never seemed to wash off in the shower.

I suspect sometimes folks jump on the softening bandwagon a little too easily sometimes. With the prevalence of folks like Culligan putting free drinking water test kits in you mailbox its no wonder.

Given all that, you've still got me wondering...

Carbon_Liberator said:

From what I understand if you are getting noticeable salt in your water from your water softener it’s because it’s not rinsing the salt out properly after the recharge cycle. I have noticed salt taste in a few people’s water who have water softeners, but never noticed it in mine, or the majority of places with water softeners.

Semipro, what method are you using to clean the sediment out of your water heater?

Click to expand...

I've used several. None are very fast or easy. I replaced the original plastic drain valve with a section of pipe and a ball valve. That allows larger chunks to exit the bottom but draining alone won't remove the sediment. The drain quickly clogs. I have to remove the lower heating element and then use a bent piece of PVC pipe inserted into that hole in the tank to drag the sediment inside towards the drain as I allow water to slowly enter the top of the tank via the inlet. Of course, the power is turned off while I do this. I've also used a auger type drill inserted into the drain pipe to remove the sediment while water flows in. The auger acts as an Archimedes screw. I've also tried adding vinegar to the drained tank to dissolve the sediment but mechanical removal method seems to work better, or at least faster.

Renaissance said:

http://mises.org/daily/5267/Why-Everything-Is-Dirtier

It's the missing phosphates, quietly removed from both laundry and dishwasher detergents for environmental reasons. It's available from the major home improvement stores in the paint section, around $10 for 5lb. Having my water softener working or idle didn't make nearly the difference that adding a Tbsp of TSP per load of dishes/laundry did.

Click to expand...

Hmm... I read the article and remember distinctly lots of public discussion about the removal of phosphates from detergents. He's right about the performance impact of removing phosphate but wrong about its adverse impacts on the environment.

The author goes on to state: "Getting even less attention was this ban on TSP in laundry soap that took place in the early 1990s, apparently codified in a 1993 law. The idea, or the excuse, was to stop the increased growth of algae in rivers and lakes (phosphate is a fertilizer too), even though there are other ways to filter phosphate, home use contributes virtually nothing to the alleged problem, and there is no solid evidence that plant growth in rivers and lakes is a harm at all."

The author is mistaken. Algal blooms in water systems are very destructive. They can be outright toxic or "just" remove the oxygen from the water column when they finally die off and decay. resulting in death to many marine creatures including fish. Also, phosphate in water is in solution. It is dissolved unless the concentration is so high that its super saturated. It can not be "filtered" out as the author states with anything short of reverse osmosis and I'm not sure that would work.

The author states that "home use contributes virtually nothing to the alleged problem." Again untrue. Phosphorus discharged to sanitary sewers is eventually discharged to waterways. Phosphorus removal during waste water treatment is not particularly difficult but it does require a extra step that many waste water treatment plants may not do, or do properly. Also, yard fertilizers are commonly misused so that nearby waterways are adversely affected.


I think I get the point of your post but just wanted to point out that there are good reasons for the legislation that lead to decreased phosphate use. Just as it was a good thing that certain destructive freons (as spray can propellants and refrigerants) were phased out of use, the removal of phosphates from detergents has had beneficial effect.

That said, I have TSP in my garage and use it frequently...and responsibly. Plants see it as fertilizer so as long as you're not discharging it into a nearby stream, lake, or aquifer it probably won't create a problem. Its much better to spray it on you lawn that it is to send it down the drain.

I find journalism like the one at the link irresponsible and harmful. Too bad, there are some that buy into it.

Renaissance said:

The author states that “home use contributes virtually nothing to the alleged problem.†Again untrue. Phosphorus discharged to sanitary sewers is eventually discharged to waterways.

Click to expand...

I don't doubt that it ends up there. I think the author is arguing that the amount in spent household detergent pales in comparison to other sources.

That said, I have TSP in my garage and use it frequently…and responsibly. Plants see it as fertilizer so as long as you’re not discharging it into a nearby stream, lake, or aquifer it probably won’t create a problem. Its much better to spray it on you lawn that it is to send it down the drain.

Click to expand...

If I'm reading you correctly, it seems like a good idea for those with septic systems.

Click to expand...

If I understand you correctly you say you doubt that stuff flushed down your toilets ends up in waterways? Or are you saying that the phosphorus is removed during waster treatment?

I"m not sure about phosphorus in septic systems. It might get stuck in the solids in the tank or it may get taken up by plant roots in your drainfield. It might also end up in the aquifer and that might be bad.

When I use TSP I do it on the lawn so that the phosphorus gets used by the grass or other vegetation instead of going into my septic or a waterway.

Carbon_Liberator said:

Semipro said:

Carbon_Liberator said:

Semipro, what method are you using to clean the sediment out of your water heater?

Click to expand...

I've used several. None are very fast or easy. I replaced the original plastic drain valve with a section of pipe and a ball valve. That allows larger chunks to exit the bottom but draining alone won't remove the sediment. The drain quickly clogs. I have to remove the lower heating element and then use a bent piece of PVC pipe inserted into that hole in the tank to drag the sediment inside towards the drain as I allow water to slowly enter the top of the tank via the inlet. Of course, the power is turned off while I do this. I've also used a auger type drill inserted into the drain pipe to remove the sediment while water flows in. The auger acts as an Archimedes screw. I've also tried adding vinegar to the drained tank to dissolve the sediment but mechanical removal method seems to work better, or at least faster.

Click to expand...

Hmmm? I tell you why I ask, I replaced the bottom element in my, relatively new, hot water tank last fall and noticed I also have a large pile of sediment in there. So much so that the bottom element was actually buried in a pile of that sediment and probably what contributed to it burning out. It was a huge element though, never seen one like that before, It was curved to conform to the shape of the tank and folded over on itself, so that the full length of it was about 6 ft long. I think the biggest one I could find in the local stores that I replaced it with was only 18" long.
Anyway, I digress,,,,, I tried flushing out the sediment, but encountered the same problem you mentioned that the sediment would plug up the small 1/2" drain valve. I did manage to get some out and went ahead and installed the new element, but I really would have liked to have clean out all that sediment. After I went online and researched a bit and found one method I haven't got around to trying yet, and that was to use a shopvac connected to a small piece of PVC pipe to get through the lower element opening and suck out the sediment. I haven't tried it yet, but was wondering if you were using that method.
Really these tank manufacturers should build a small 6x6" access plate near the bottom of the tanks for cleaning out sediment. maybe some do, I don't know? Next time I'll be looking for one that does i know that.

Click to expand...

This all sounds so familiar. I tried the shop vac but the pipe the hose was attached to would get clogged easily. I haven't yet seen a water heater with the access plate at the bottom that you mention. If they would just make the hole that the drain valve screws into larger that would help a lot. I think a lot of folks replace their water heaters way too often because of this issue.

Renaissance said:

If I understand you correctly you say you doubt that stuff flushed down your toilets ends up in waterways? Or are you saying that the phosphorus is removed during waster treatment?

Click to expand...

Neither. I said "I don't doubt". I'd bet a lot more phosphorus goes down the toilet, than through the drainpipe of a dishwasher in any given week. I think the author was suggesting that the marginal environmental benefit of removing phosphates from detergents isn't worth the sacrifice of dingy clothing and dirty dishes.

Click to expand...

My mistake. Thanks.