SG of Tap Water

[85 Haro Designs]

Well as the scale tips up on the wallet side and down on the equipment side my homebrewing equipment arsenal gets larger. After my 3rd trip to my LHBS in as many weeks I continue to "hone" my skills with my new found love for all-things-laboratory. By 2009 you can call me "Beaker"!

My question is this........my tap water reads = 1.005 SG - at 60°F (which is what the floating hydrometer is calibrated to). Has anyone else tested their tap water's SG?

Is this a normal reading for tap water. Am I fretting over thousandths for nothing? Please provide tutelage where needed.

 

[shafferpilot]

Tap water should read REALLY close to 1.000 (mine is dead on). Sure there's other stuff in there, but it certainly shouldn't be reading .005 off. Check distilled water and note how far off the reading is so you can adjust your future readings. Also, remember to read the hydrometer at the average liquid level, not where the liquid "ramps up" to the sides of the hydro.

 

[85 Haro Designs]

Thanks for the early morning quick answer.

I'll try distilled H2O per your suggestion and I'll also check bottled water as well and record my readings of all three for future reference.

I did take the average height reading - not the top of the miniscus (or ramped) area. I didn't know that but I guessed that's how you would read it.

If anyone gets a chance, could you check YOUR tap water as Shafferpilot and I have done.

 

[Funkenjaeger]

My tap water is almost indistinguishable from distilled - in my case, both read 1.002 corrected for temp, meaning my hydrometer is off by .002.

If you are reading 1.005 I would be quite surprised if that's all due to the actual water and not an offset in the hydrometer that you need to calibrate out.

 

[85 Haro Designs]

It appears that when the water temp reaches 68°F that it could be close to SG 1.00. If this is the case - would it be safe to assume that as long as my sample is 68°F - I can consider this my NEW calibrated temp?

(Again my hyrdrometer / thermometer combination says it's calibrated to 60°F)

 

[david_42]

Certainly, just be careful when you use the adjustment tables.

 

[shafferpilot]

There's something amiss here. A temp swing of 8 degrees shouldn't be making a .005 difference. More like a .001 difference. What adjustment does your temp calibration table give you for 68 degrees?

 

[85 Haro Designs]

Shafferpilot - you're astute to notice that something is amiss. After waiting for the temp to read 68°F of the tap water, I would say the reading on the hydrometer was around 1.003 as a best estimate.

To be honest, I spent $12 for this hydrometer / temp combination and I'm not impressed with it's overall craftsmanship. I mean, I know they're probably made in a sweat shop in Shri-Lanka but it REALLY looks like 2nd rate goods.

I bought it from a reputable online retailer (which shall remain un-named at this time) and I'm sure it's the same one everyone is else is using, since the picture in all catalogs looks exactly like this one.

It just kinda ticks me off that I'm .005 off of basal SG.

 

[reshp1]

Read the instructions for the hydrometer. Mine specifically says read from the miniscus, which could account for the 0.003

 

[Yooper]

Well, the tap water reading is meaningless anyway. Try using distilled water, and see if it's still off. If it is (I have one that is), just subtract or add the difference to your samples. I have one that is always .002 high.

 

[shafferpilot]

honestly I am amazed that mine is dead accurate. The one I broke a month ago was .002 off. It's the price of mass production. Personally, I'm the kind of guy that is quite willing to spend extra money for a high-quality tool.... But after breaking my second hydrometer by simply whipping it to remove rinse water, I just decided that they were expendably cheap hunks of glass. If anyone knows of an AMERICAN manufacturer of quality hydros, let us know...... yes I know that refractometers are an upgrade option, but I'd love to have a hydro made from high quality pyrex or something tough like that. Any lab technicians with suggestions?

 

[wildwest450]

Well, the tap water reading is meaningless anyway. Try using distilled water, and see if it's still off. If it is (I have one that is), just subtract or add the difference to your samples. I have one that is always .002 high.

What if your using the tap water to brew with, wouldn't you want your hydrometer calibrated to that?

 

[Yooper]

No, because you boil the wort and you want the sg of the wort, not of your tap water. You want an accurate hydrometer, so it should be calibrated with distilled water. I wonder- if you boiled your tap water if then it would be closer to distilled water? I'm not sure about that. It might be worth a try.

 

[wildwest450]

No, because you boil the wort and you want the sg of the wort, not of your tap water. You want an accurate hydrometer, so it should be calibrated with distilled water. I wonder- if you boiled your tap water if then it would be closer to distilled water? I'm not sure about that. It might be worth a try.

I may try that, my stupid hydro reads 1.005 in my tap water.

 

[wildwest450]

I may try that, my stupid hydro reads 1.005 in my tap water.

I just boiled some water, and no difference, still reads off. As I was doing this, I couldn't help but think that Yooper was taking me on a snipe hunting adventure.

 

[Yooper]

Sorry- no snipe. I just was thinking out loud (out typing?) that distilled water is basically boiled water with no mineral content. I thought maybe it might be similar that way. My hydromter read .002 high in distilled water- so I just always subtracted .002 from my readings. It was easy, and no problem. That's a very small difference, regardless, so I didn't worry about it. But .005 would irritate the heck out of me!