Jimagination 
If you want to just clean the waterers, you can use white vinegar. Rinse well.
It is the apple cider vinegar with the mother that provides probiotic effects to your flock. Don't mix ACV with any vitamins/electrolyte solution. 
About Garlic... I could write a book...
Garlic is extremely effective in dissolving and cleansing cholesterol from the blood stream, it stimulates the digestive tract, is a known immune system booster, kills worms, parasites, and harmful bacteria, and is said to reduce fever and ease muscle cramps. Garlic will also disinfect wounds and ease a toothache.
Antibiotics can be given, but while they kill harmful bacteria in the digestive system, antibiotics also kill the good flora. Garlic provides a similar type of protection but without harming beneficial bacteria. 
Fresh garlic can be used for infections, coughs, colds, flu, bronchitis, fevers, pulmonary conditions, gastric and skin complaints, rheumatism, all worms and also liver fluke, ringworm, ticks and lice. 
It is said that many types of mites and fleas will not feast on animal with garlic in their skin. Which could be why our dog and cat don't have bug problems. Crush 1 or 2 cloves of garlic per bird and mix with feed.
I just put freshly crushed garlic on top of their feed. They love it!
I add freshly crushed garlic to plain fat-free yogurt with active cultures or to low-fat or fat-free low-sodium cottage cheese 2 or 3 times a week. 
Two cloves of garlic per bird is given as a natural wormer. The yogurt provides beneficial bacteria. 
I put the mix on top of their feed in a separate bowl or spoon feed them. No, I'm not kidding. Our birds forage our two acres and they will readily follow me back to the barn if I have a spoonful of yogurt or cottage cheese with garlic handy. 
Another method is to crush the garlic cloves and put them into a stocking. Leave the stocking to hang in the fowls water for a week. 
One teaspoon of crushed garlic with the oils mixed with one cup of olive oil and left to cure for about four weeks in a sterilized jar in a dark cupboard can then be drained and used as a pest spray in the hen house or on chickens or pets. ..Or your pasta salad or dog's or cat's food...  
If you grow your own garlic, you can occasionally feed garlic greens to your birds.
You don't want to put garlic in the water the same you are feeding them garlic. And no garlic in the water with ACV. 
I have heard that garlic taints the eggs, but we haven't noticed any problems.