Whether you are travelling around Sri Lanka or live here permanently, there's one thing you won't be able to avoid, and that's eating (and in a country with such amazing food, seriously why would you want to??)
But there are a few things that tend to come along with the ride when eating out that I'm sure you are more than happy to go with out, those being:
a) Getting Ripped Off
b) Getting SICK!
So here I will give you a few tips that will help you get an amazing meal for a great price that won't leave you running to the bathroom every 5 minutes after eating it!
Find out the price BEFORE eating
This one is pretty straight forward, and is pretty much the same rule for everything you are going to be paying for in Sri Lanka, that being, always find out the price of what you are ordering before actually ordering it. This way there will be no big surprise at the end (and unfortunately once you have already eaten the food, its very hard to try and negotiate the price afterwards.)
We got caught here once unfortunately, spending 1500 rupees on 2 rice and curries (that else where we would have been paying about 300 rupees). Sure the food was amazing (as it always is) but for a price tag like that it was definitely a lesson learnt!
Drinking The Water
If you are eating at the small local cafe's (which hands down make the best food!) then generally someone will always bring you a glass of water out of the tap when they bring your meal to you. I often get asked by people whether you can actually drink the water, or if you must just stick to bottled water over there, and all I can give is my own experience.
Personally I drink the tap water. I started off avoiding it like the plague when I first got to Sri Lanka, however after awhile to be perfectly honest I just felt like giving it a go for the sake of it. I will admit that when I first started doing so I did get a slight stomach ache afterwards, however i cannot say whether it was in fact from the water itself, or just a coincidence (I'm not a doctor), but after the first couple of times there was no issue and hasn't been since.
So keeping that in mind I would look at it this way, if you are just holidaying for a few weeks or so, maybe stick to the bottled water alone. But if you are staying for an extended period of time and want to get accustomed to the local water, then it won't kill you (and it will be cheaper than buying a bottle of water each time).
Avoid 'Touristy' Restaurants
Again, this same rule applies to pretty much all purchases you will make in Sri Lanka. That being, avoid the touristy places! These will always cost you more, and sure, if you are on a holiday and want to splurge then go for it, but the prices will add up fast (especially when instead of spending 2000 rupees on a western style meal, you are spending 120 rupees on a massive rice and curry that is 10 times better!)
Bring Hand Sanitizer
This is for just in case. You do need to remember that this is a third world country, and the sanitation levels are slightly different to what you will be used to in most western countries. Most of the cafe's will have a wash station in the restaurant for washing hands, along with soap, but if hygiene is highly important to you then this may be something you might want to bring everywhere with you before eating.
Food stalls
From my experience, the little stalls on the side of the road have been fine. I haven't gotten sick from them and have grabbed the occasional roti or spring roll from time to time, but when it comes to food that's been sitting there for awhile it's obviously important to approach with caution.