Regular black, green, & orange-pekoe type tea contains fluoride "naturally," as the tea plant concentrates/pulls fluoride from the soil. Different brands & varieties may vary somewhat in fluoride concentration, depending on the native fluoride concentration in the soil where the plant is growing. There is some discussion as to whether organic teas might contain less fluoride, as they are not subject to additional (possibly) fluoride-containing pesticides/herbicides that conventional tea may be subject to. Decaf regular teas still contain fluoride. Herbal teas contain much less.
Dental products are a major source of fluoride. Not just the at-home stuff -- the professional dental office products often contain high concentrations of fluoride.
How much fluoride is in drinking water depends on the locale. A few areas have "naturally occuring fluoride" in drinking water. Many cities & counties rountinely add fluoride to drinking water -- you have to ck with them to find out 'how much.' The majority of bottled beverages in the USA -- sodas, waters, juices, etc. are made with fluoridated water.
Fluoride is not easily removed from water. Standard carbon filters like Pur & Brita remove chlorine & metals, but don't get out fluoride. For that you need a reverse osmosis filter, which is spendy.
The skin absorbs fluoride (& chlorine) during showering & bathing. Many of us are also exposed to airborne fluoride from manufacturing. Progress has been made in recent yrs. with emissions scrubbers, but there are still accidents & leaks. Aluminum & other refineries formerly released TONS of fluoride into the atmosphere annually. This of course does get into soils & water.
Food carries an increasing fluoride load, due to increasing loads in soils, as well as to increasing use of fluoro-based pesticides. The fluoro-based pesticides are especially nasty as they are persistent accumulators not easily dealt with by the body's built in toxin-removal systems. There has been increasing acceptance of the use of cheap industrial/sewage sludge as fertilizer, however sludge is typically high in fluoride, heavy metals, and other industrial waste, none of which is particularly health-promoting. Organic food grown in areas of low native-soil fluoride, will contain less fluoride than some conventionally-grown crops.
Many fresh cherries in my state are grown in orchards next door to a major (former/currently inactive) aluminum smelter. This fruit is very high in fluoride content. The region was formerly an apricot-producing capital, but the fluoride killed apricot blossoms & so those orchards were removed to make more room for cherries, which were tolerant of fluoride.
If you're interested in more specific information, there are many fluoride activist groups with details & scientific studies. These are not all Chicken Little/Fearmonger organizations. The EPA itself has a large number of scientists who are becoming increasingly vocal about the myriad of health risks we face from modern-day multiple-source exposure to fluoride, with actually very little proven dental benefit. Most testing reveals that the majority of us are ingesting/inhaling/absorbing many times the safe amout, and our children, with their smaller body masses, are quite at risk.
Vets use tamarind (a sweet/sour date-like fruit) to detox pets w/fluorosis. Tamarind has a fascinating ethnic history in India. Near-epidemics of fluorosis & mental illness occurred when people in certain high-fluoride water areas replaced traditional tamarind in home gardens (& diet) with tomatoes.
Tamarind chemistry is a little complex, as the plant binds fluoride from the soil & so does itself contain some fluoride. However, urinary excretion studies suggest that tamarind ingestion leads to significant net excretion of fluoride from the body. It has even been shown to remove fluoride from the long bones. (Fluoride excess has correlations w/bone cancers & osteoporosis.)
High-dose iodine (50 mg/day 2-3 months, thousands of times the RDA) has been shown to cause the body to release stored fluoride & bromine/bromide. However, iodine supplementation is controversial at present. Historically, iodine supplementation was standard medical treatment for thyroid disorders, both hypo (at much lower levels than 50 mg/day) & hyper. Current research suggests that high-dose iodine supplementation may suppress thyroid function.
IMO in iodine-deficiency states, fluoride is more likely to bind to iodine receptors.