To make a long story short it's not easy to get my horse trailer very close to a hydrant to fill with my white hose.  It will be very rare we use the shower, we might use the sink to wash hands but that is about it... the majority of the time we will use the water just for the toliet.  If I use a regular hose to fill my fresh water tank will I get bad water (whatever that means) just that time or do I mess up my system for future trips?

I believe that if you'll flush the hose first before filling your tank, you should be OK. The water won't be in the hose long enough to become contaminated or aquire that "funky taste/odor".....!! The older "garden hoses" were made using a small amound of LEAD. This kept the hose plyable and flexable. I even flush our hoses each time I fill the horses water buckets, specially in the warmer weather with the hose being baked by the sun.

Do you use well water or are you on a public water service??? Chlorine, fluride, etc...

Well water.

We use a regular ol' hose to fill ours with.  You stand a better chance of the water getting a stink from setting in the tank than you will from filling up from a standard hose..

If I remember right the "white hose deal" is mainly if you are going to be hooked up to shore water supply.

Keep it, you never know when you may need it.  I keep 2-25' hoses and 1-10' hose (all white RV hoses) in our trailer now just because 2 year ago we was down arond Houston at a trail challenge and the hook ups was at the back of the trailer and at that time our water hook up was almost 40' away and we run out of water.  NEVER AGAIN.  Better to have too much than not enough.

My understanding of the white hoses is this - they are more essential if you keep your trailer connected to a water source than if you simply fill the trailer quickly and then disconnect things.

A hose is like a plastic water bottle. When water is left for a long period of time in a water bottle, it tends to leach some plastic residue into the water. This is accelerated when the water warms, such as when a bottle is left in a summer car. Some sources state the process is also accelerated when water is frozen, so they tell you to not freeze water in your water bottles. On the other hand, I've read other information that states leaching is lesseoned when water gets cold or freezes. But one way or another, water can pull chemicals and such from plastic when in contact with it for long periods of time.

I believe your garden hose is the same way. If you simply fill your tank with a regular, clean hose, the amount of leaching from the hose is very minimal and shouldn't cause problems. By the way, taste might be one of the problems, because we all know that garden hoses can give water a "rubbery" taste if they sit too long in the sun! But if you plan to connect your trailer to a city or campground water source, then you potentially could have a bigger need for the white hoses.

Make sense?