Leakproof Plastic Bottle

I just use any bottle of the correct size and put it into a small plastic bag. I think I used a travel sized mouthwash bottle to take some woolite with me on my last trip. Have not had any leaks yet.

Regardless of the bottle used, it never hurts to place it in a small freezer zip lock bag just in case it does leak or fracture. Has saved us from having a mess on several occasions.

I have only had leakage from those expensive Gotoob silicone things. My little Nalgene bottles I bought as an assortment from REI have been reliable and leak-free. For Dawn I would use one like this: ( have to go find a photo).

Edit---cannot find a photo but the Nalgene bottles sold by REI should work fine.

Nalgene bottles from REI have never failed me.

Third the recommendation for Nalgene bottles. I got mine from The Container Store.

I've used Nalgene bottles for decades. Never a leak.

Another yes on Nalgene bottles. I've landed (fallen) on Nalgene water bottles with no damage to the bottles. Container Store has the smaller (than water bottle) sizes:
http://www.containerstore.com/s/travel/bottles-medication/nalgene-round-leakproof-bottles/12d?productId=10000243

The only reason for placing a Nalgene bottle in a Zip-lock bag is to conform to the 100 ml air travel carry-on rule.

If you want a guarantee, then place it in a plastic bag.

"Another quote for my book, "How not to pack light"."

Another quote for MY book, "How to be Judgey McJudgerson about other people's packing and travel styles." One extra three ounce bottle isn't exactly "not packing light."

Now, I myself don't pack dishwashing liquid, but I assume Mark has his reasons for doing so.

A little tip to prevent leakage from any bottle.

Cut a small piece of Saran Wrap/Cling film and put it over the mouth of the bottle. Then put the cap on. This should prevent any spilling or leakage especially in a pressurized aircraft.

A small amount of dish soap is a great anti-fog treatment for snorkeling masks. I would bring it if I were going on a short trip to a remote snorkeling area.
It's true though, that little bits of liquid add up into pounds.

I vote for itty bitty Nalgene bottles too. You can order tiny ones in .25, .5 oz sizes off the Internet.

Or just use an old eye drop bottle. They are usually around .5 to .75 oz. I've never had my eye drop bottles leak. They're designed for transport in people's purses and brief cases so the cap mechanism is fairly robust.

Paraphrasing Everett Dirksen, "an ounce here. an ounce there, pretty soon you're talking about real weight."

But seriously, this is one of the ways people pack too heavy. "It's just I'll take this, it only weigh a few ounces." "I want to take this, it doesn't weigh much more." Pretty soon your bags is too heavy (you think) to carry. You need wheels. Then it's too heavy to carry on. Packing light takes discipline; you have to avoid the temptation to take just a little more because it "doesn't weigh very much". They do sell dishwasher soar in Europe.

A small amount of dish soap is a great anti-fog treatment for snorkeling masks. I would bring it if I were going on a short trip to a remote snorkeling area.
Minimalist would suggest leaving the dish soap home and just using spit. But then again, if you are packing snorkeling gear, you may want to check your dive gear and would have a lot of space/weight capacity to bring a couple of oz. of detergent.

Travel imposes compromises. If bringing a couple of oz of dish detergent brings someone happiness, why should the peanut gallery be so down on someone else's happiness. If the two oz of soap is the perverbial straw that broke the traveler's back, he won't do it the next time.

Traveling light brings back memories of early backpacking days where some minimalist would cut of half the handle of their toothbrush. I on the other hand packed in my toys including my SLR with extra lenses along boxes of film and fishing gear.

I don't think the decision about incidental consumable products (like liquid soap) is clear-cut. I don't agree that "Just buy it in Europe" is always the right answer. If you can take a 1-oz. bottle from home and the product is only available in much larger bottles in Europe, how does it help to buy overseas, unless you are spending the entire vacation in one place? Why would you prefer to carry a large bottle through Europe rather than a tiny one? That makes sense only if you're trying to do carry-on-only and you expect to need more than 3 oz. of something.

The difficulty, of course, is that in many cases we must decide about a product we may, or may not, actually need on any given trip. Experience helps with that type of decision, but there's luck involved in getting it right. I think a few ounces of insurance in the form of duct tape, Scotch tape (for map repair) and OTC medications is worth it. I'm fanatical about other things--no jewelry, only one pair of shoes, the slimmest/lightest fountain pens I can find, no heavy garments, carefully-calculated amounts of things like toothpaste and hair conditioner, etc.

I haven't tried dishwasher soap as an anti-fog treatment. I have had good luck with hard (or gas permeable) contact lens wetting solution. A drop rubbed on the inside of each lens works. It also has the benefit of no risk of stinging your eyes. I suspect rewetting eye drops might work, too. And you can buy eye drops in very small squeeze bottles. You can get contact lens solution in small bottles, but it is harder to find and is more expensive. Interestingly, the generic solution seems to work better for me than one of the name brands.

I buy the small bottles of hand sanitizer - flip top cap and squeezable - when empty I remove the labels and they work great for liquids in the 3-1-1