Dropped iphone 4 in water.seems fine?

I dropped my iphone in a bucket of water (oops!) it has a cracked screen front and back and was completely submerged.unfortunately i was working in a barn so needed my phone and and had no access to rice so had to keep using it. Only problem that happened was it would keep switching my headphone volume all the way up randomly but a couple hours later that seems to have stopped.i've already had my phone on so not much point in rice right? But could the insides still get water damage over the next few days or am i okay?

When phones are liquid damaged they are classed as BER (beyond economic repair).

The inside of a phone is made up of metal parts and circuit boards - meaning the liquid will slowly corrode and rust them. As this can sometimes be a slow process (depending on how much liquid got in the phone) this is why some phones appear to work for a while after getting wet. But they will eventually fail as the corrosion inside stops them working. Liquid damage can occur by the obvious drops into water but also through condensation/steam and rain damage.

Some tips you may read such as putting it in rice or in the airing cupboard may work in the short term, but the phone will stop working and is irreparable as the inside of the phone will corrode.

If you have insurance on your phone you would be able to claim through it, or maybe you can claim through a home insurance policy. Any type of liquid damage is not covered under the manufacturers warranty.
If you have no insurance plans then I'm afraid your only option is to buy a new phone.

You will probably find that your SIM card and memory card are ok if removed from the phone promptly after the damage occurs.
If the SIM is damaged you can get a free of charge replacement from your network. If the memory card is damaged, unfortunately you won't be able to retrieve its data but you can replace memory cards with new ones.