If water is made from covalent bonds with no ions, why is it a conductor of electricity?
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Pure water isn’t a very good conductor. But insofar as it conducts electricity at all, it does so because water *self-ionizes*: water molecules occasionally tug a hydrogen ion off of other water molecules, forming a hydroxide ion and a hydronium ion: 2 H2O <-> OH- + H3O+. At any given time, around [1 in ten million](https://en.wikipedia.org/wiki/Self-ionization_of_water) water molecules in solution is temporarily one of those two ions.
(As an aside, it can do this because water’s bonds aren’t exactly “pure covalent”. Covalent and ionic bonds exist on a spectrum, with totally symmetric covalent bonds [like the nitrogen-nitrogen bond in N2] at one end of the scale and totally ionic ones [like bonds between halogens and alkali metals] on the other, and polar covalent bonds in the middle. Strictly speaking, all bonds have some of both; we just categorize them into those groups because most bonds are strongly on one end or the other. Water, as it happens, is polar covalent, so it hangs out in the middle of that spectrum. On a scale where pure covalent bonds are a 0 and highly ionic bonds are a ~10, water sits at around 3: more covalent than not, but with significant ionic character too.)
Normal water is a very good conductor because it is extremely good at pulling ionic compounds apart into their constituent ions. Table salt, for example, is pulled apart from NaCl -> Na+ and Cl- to such an extent that NaCl basically doesn’t exist at all in solution (it’s virtually all ions). It’s those ions (called “electrolytes” in this context) that make impure water conductive. Since there are far more of these pulled-apart ions than there are self-ionized water molecules, water with any dissolved minerals is much more conductive than pure water.
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