RiseAC
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Tap Water vs. Distilled

Hello all, I'm no gardener nor will I pretend to be one. I'm a SUPER newbie and I have a super newbie question. I'm doing a science fair project with my son and he is trying to see what kind of water will facilitate the growth of a little bean seed. The 4 waters we used are salt, tap, spring and distilled. His hypothesis is that the distilled water, being the most free of impurities, will facilitate the most growth. The bean in the distilled water cup is coming along nicely, however, after two weeks, the bean in the tap water has exploded in growth and the stem and leaves are now poking out of the top of the cup.

What about the tap water lead to something like this?

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applestar
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Re: Tap Water vs. Distilled

Is he at the reporting stage of his experiment? Is he stumped for explanation?
We shouldn't tell him the answer just yet, I should think? Give him the time and chance to think about this a bit more....
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RiseAC
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Re: Tap Water vs. Distilled

Yes. For the first 5 days there was no activity in any of the the four cups (he was watering lightly every two days and it has been cloudy and cold here in S.E Texas). Once we started getting sunlight it took only two days until a small stem began to poke through the bean in the distilled water cup.

A few more days and both distilled and tap water cups have sprouted a little stem and leaves. Two more days later and the tap water plant is much bigger while the Distilled water plant has remained unchanged. We're pretty confused as to why.

Image

HoneyBerry
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Re: Tap Water vs. Distilled

There are other variables that affect sprouting. If you were to use the same type of water on all of the seeds, there would be variability in the sprouting anyway. Some seeds will sprout faster than others and some won't sprout at all. That's how it seeds are naturally. I don't think you can conclude that the results were only because of the type of water used.
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Allyn
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Re: Tap Water vs. Distilled

You didn't say if your tap water is city water or from a well, but there are things in the tap water that aren't in distilled water -- minerals perhaps? -- that the plants may benefit from. Birdlover is correct, though. Seeds out of the same batch will sprout and grow at different rates. Doing an experiment with a single subject for each water type isn't going to let you draw any conclusions about the water.

These are three of the beans out of my current seed starts:
Image
All three came out of the same seed pack, planted at the same time in the same medium and receiving the same water and watering routine. The one on the left isn't sprouted (and may not sprout at all). The one on the right is growing very fast.
Last edited by Allyn on Wed Jan 27, 2016 7:02 pm, edited 1 time in total.

RiseAC
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Re: Tap Water vs. Distilled

Wow that's amazing. I was unaware that the variance in growing could be so great. I was expecting them to grow generally around the same time with some being a little taller or shorter than others but not to the degree that some wouldn't sprout at all.

To answer your question, this is tap water from the city. We also assumed that there may be some extra minerals in that water that would be more conducive to growing which would explain the explosive growth of the bean seed in tap water. Fortunately this is only for a 4th grade science fair so we won't have to go too much in depth about irregular growing patterns or tap water contents.

I thank all of you for your quick responses, you've helped out a lot!!

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Re: Tap Water vs. Distilled

So far as I am concerned you have deduced the answer....to this point. See how things go for the amount of time allotted to the experiment. See whether your tap water source will give you the chemical breakdown of the water supply. This could get bonus points for going beyond the call of duty and would be helpful in the conclusions drawn.
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Re: Tap Water vs. Distilled

PH has an affect on seed germination. Pure distilled water has a neutral PH that is easily changed if the water has impurities. The PHs of the different types of water may have influenced your seed sprouting rates, but once again, PH is not the only influencing factor.
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imafan26
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Re: Tap Water vs. Distilled

Distilled water if it has been boiled, steamed and condensed will not have any salts in it.
Tap water may contain small amounts of minerals calcium, magnesium, and even algae depending on the water source. Your board of water supply should have a water analysis available if you contact them to find out what is in the water. I get periodic water quality reports. We actually have pesticide and oil residues in our water from many years of agricultural infiltration into the city system, cars and leaking storage tanks. The water in my area goes through charcoal filters and is chlorinated but you really cannot taste it. Some municipalities not only chlorinate but may also and flouride to the water.

I would be surprised if the bean seed grew at all in salt water. Now, if you were growing asparagus, that might be a different story. Asparagus is salt tolerant.

If you had time to reduce the errors in the experiment you could have grown a larger number of bean seeds say 10 bean plants for each water type that way you could average out the errors from other variables. Otherwise you are drawing conclusions based on the success or failure of a single seed.
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jasonvanorder
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Re: Tap Water vs. Distilled

I agree with imafan26 To really weed out most anomalies you would need to plant multiple beans for each water type. But as you said its only a 4th grade project so not a lot of time and detail needed. But for kicks and giggles it could be something you both take part of at home just to see what happens. And remember the only difference between screwing around and science is writing it down :)

HoneyBerry
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Re: Tap Water vs. Distilled

I was a science fair judge a few times. Some of the kids who had nice experiments were docked points because they didn't do the write up correctly. Be sure to do a good writeup that shows how the scientific method was used in the experiment.
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