lol Lanie,
I sometimes think ignorance really is bliss 
don't you?
First of all- there is a difference in chlorines- the chlorine that is added to the water supply is very dilute and it is not bound to anything- so it kills off the microbes or dissipates into the air. That's why you have to constantly treat a pool with chlorine- it's always escaping into the air - ever smell an indoor pool area? Nice and bleachy smelling. You can test this with a simple aquarium water test kit- draw water out of your tap, test- let stand for 24 hours and test again- the chlorine ( if any) will be gone.
The chlorine in splenda is bound to the molecule- so in theory it should just stick to your sweetness receptors like superglue, and then detach and leave your body intact. There are no sucrolase enzymes in your body to digest it because it is not a natural substance- but an enzyme like that would only dissolve the chemical bond between both halves of the molecule even if it did exist, not act on the chlorine. Again- chlorine is very reactive and not all of it is excreted- so it has to be in your body. One thing your body does is make little storage vacuoles in fat cells to sequester the poisons it encounters- that's why people who do long term fasts usually get really sick- as those fat cells break down, all of the toxins are released along with the stored energy molecules. Over time, you could build up a good amount of chlorine reserves- esp kids whose little bodies are growing, adding fat cells and so forth.
As for tap water- I don't use it. I have a charcoal filter attached to my water supply. Kind of like a Brita water filter on steriods. All my water passes through that- it is not a softener which runs water though salt. I also have a distiller- and I distill all water used for cooking and coffee. (You can buy this type of water cheap at WalMart.) I use bottled mineral water, high in natural silica and rich in minerals for drinking- I periodically test it to be sure it has what it advertises- One of my friends works in a water quality facility and runs a sample for me every now and then - I bake her department cookies as a thank you!
Stevia is the only natural sweetener on the market- most of the others have been discovered in insecticide labs- you should do a search on it for some fascinating reading. I have long used equal and sweetnlow as ant repellants (they are smart enough to stay away from it). I do use them to sweeten on rare occasions when I don't have any stevia with me. If you use too much stevia- it leaves a licorice like after taste. There are so many forms now that if you sampled you might find one that you like.
I recently received some free packets of Zsweet. (www.Zsweet.com) It contains erythritol- a sugar alcohol with the least amount of glycemic impact- and natural flavors (no dextrose or maltodextrin, although I think Bernstein might have got it wrong on the maltodextrin- it's not readily digestible and acts like a fiber not a sugar as far as I can determine biochemically). It's not as sweet as the artificials, and didn't cause any type of gas or intestinal woes. I'll bet they are still sending out freebies if you want to try.
I also heard that there's a milk sugar based sweetener coming out- I haven't seen it yet. Milk sugar is a disaccharide (double sugar) that contains 1 glucose molecule bound to a galactose molecule. Galactose had no glycemic impact, so this sweetner would be natural but should have 1/2 the glycemic impact of sucrose (2 glucose molecules bound together).
Aren't you sorry, you asked me the splenda question now? lol
I actually did one of my research rotations in an insecticide lab and my boss was always telling us how we could get rich if we could just develop another artificial sweetner. Patents and $$$ galore- I was always afraid to taste my work.....
sandy