Switching from a Govt. job to teaching Geography

Actually, you should have given your qualification to know whether you are eligible for a teacher post. Now you are working in a government department.
To become a teacher in a school you should have passed minimum 12th class or equivalent and you should have a diploma in education. Once you have these two qualifications you can apply for a primary teacher post in any government school. You can teach all the subjects in primary school.
If you are a graduate, you can do B.Ed course. Only candidates having B. Ed qualification only is eligible to apply for teacher post in high school. You can opt for Social studies in your B.Ed so that you can teach social in high school.
If you are a postgraduate or a doctorate you can apply for the UGC NET examination and once you qualify you can apply for lecturer posts in various colleges and universities. You can become a lecturer in the subject you have studied in your PG. If you are a PG in geography you can become a lecturer in geography.
But don't leave the present job till you get a teacher post if you are having the qualifications. Continue in the present job and try for the teaching post. Getting a government job is very difficult these days. So don't quit. Please remember that a bird in the hand is worth two in the bush.

From the question it is not clear what is your actual query.
Are you asking about just an opinion in quitting this job and taking up another job? Or are you asking for the procedure and how to about it?

Hence I assume that 1. You have all the minimum qualification needed to apply for a Geography teacher Job .
2. You are within the maximum eligible age to apply for a teacher job.
3. You are qualified and eligible to apply both for a teacher job in Govt institution as well as in private institution.

Assuming the above 3 points, I give my suggestion:

1. It is always better to take up a job where your mind is there and you are interested.
2. But it is not prudent to quit the current job (where you had already put in 5 years service) without getting the teacher job. Hence start applying for the teacher job vacancies or sending your bio-data to the prospective employers.
3. You have to update yourself on the subject as well as in the emerging digital-online teaching abilities.
4. As job satisfaction may not be a long sustaining one in the future when one has a family and family needs, assess your career enhancement opportunities in the present job as well as prospective job too. Then take a decision considering al the pros and cons.
5. Try to enhance your qualifications in such a way that it will help in getting better openings in teaching assignments. You may also take up courses helping to achieve additional qualifications f the same level or higher levels.
6. Read a lot on the subject you are interested and try to write articles and other works on that which ma help you in your teaching job prospects.
7.Prepare yourself for the qualifying tests for you prospective teaching job vacancies.

8. Last but not least resign the present job only on getting a better or aimed job.

Best wishes.

By going through your incomplete question, the answer would be accordingly. I would suggest you to continue with the current Job in Government service. Do not quit the current job just because of the interested in Geography teaching job.

You can teach the Geography for the deserved candidates (as free or with nominal charges) during your off-duty or leave etc. so, think wisely before jump in.

In case if you are seriously would like to go with that profession (Teaching in Geography) then you can apply for the same when opportunity arises from Government or Private firm.

At present, you are in working in the state government have rendered your service in Water Resources Management for five years. The job is stable in terms of security and as such I would not advise to take up any experiment endangering your stable services.
It is really very fascinating that you have intense inclination towards Geography. However, you have not indicated your qualifications details so that I could correlate your prospects as a teacher of Geography.
Supposing that you are a graduate taking one of the combination papers as Geography but simultaneously, you need to have a B.Ed degree so that you can switch over your career as a teacher. Now you will have to devote your timings for the persuasion of B.Ed either through the regular mode or through the private one. Regular study for B.Ed would mean dislocation of your present job and as such it is not advisable. At best, the same can be taken up through the distance mode such as IGNOU, Kota Open University or Karnataka Open University etc but this calls for a disciplined approach to manage both your current job and your further studies.
In case, you are having a post graduate degree in Geography with the minimum aggregate of 55%, you can think of UGC NET so that you would get the chance of lectureship in a government college.
The rout, though difficult, does not signify that you cannot proceed further but the same should not be done risking your present government job. You will have to think pros and cons before you take a final decision.
At best, you can be a tutor in Geography and can start teaching to the pupils studying in the high school with the combination of Geography in your free time. With your passion and interest, you can have huge income for such an avocation apart from the income from the present government job. However, you will have to take up permission from the present authorities before taking up such assignments since a government worker is not permitted to take up any job unless there is a concurrence of the parental department.

You are working in State Government water department which means you are already having a good job in hand. Your keen interest in teaching geography shows that either you have interest for teaching or you have already got a degree in geography which you want to utilise for teaching geography to the students. Anyway, that is only my assumption and if you don't have a degree in Geography then you will have to acquire it in order to go for teaching Geography in a school or a college or a university. It is imperative that accordingly either you should have a simple graduation degree in Geography followed by B.Ed or you can go for a post graduation in Geography followed by NET test or go for PhD in geography and then try for getting a lecturer post in a university or college.
Are you in a position to acquire these qualifications or the remaining ones if you already have partly some of them? If yes then you can think of going ahead in that direction.
Please note that acquiring the qualifications at this stage is a risky proposition as you would be taking the risk of leaving the present job which being a state goverment job is definitely a lucrative one.
Switching a job in today's situation is not an easy task as the job conditions are tight everywhere and even for the teaching area there is a long queue of qualified people struggling to get a teaching job.
Take all these points in consideration and then take a calculated decision in the matter.

Teaching is one of the noble professions on earth. It teaches the very basics of life to the people and makes the earth live worthwhile. Leaving your government profession or job is your personal choice otherwise normally people aspire to become a government servant in such a type of job. You have not mentioned your qualifications, so it is very difficult to judge where you will be working as a teacher in school. If you want to teach geography as a tuition teacher or in a private school with the right kind of qualification, you can. For government school, you have to apply for that job through proper channel by exam and interview.

Follow your intuition. May God bless you.

Quitting a present job is not a good option at all if your ultimate priority is job security. But, if you love taking risks and have enough savings so that you can easily quit for one year and prepare for a teaching career then you can go for it. First, you have to decide what you want to do, job as a government teacher or in private schools. If you want to be in the government department once again then first check whether you are eligible or not. As you have not mentioned your qualifications also your age would also be considered for government job examinations, so also consider this. Moreover, if you want a private job then you also require some teaching experience or in another case some good references. It is good to go with passion but it is always advisable to have a well-developed roadmap before following passions because at the end of the day you have to feed yourself and your family.
Moreover, as you mentioned earlier you want to teach geography as you are interested in it, so why not create a YouTube channel or link yourself with some NGO as a teacher and with that continue your present job. This would serve both purposes, i.e. your interest would be served and in addition to that, you have secured a job.

It would not be prudent decision to quit present job. As mentioned above you have been working in state government water resource department for 5years. No doubt you are in safe position. These days it is not easy to get govt job. In your case you are already in decent job and want to leave. You must think before change your career. It is very nice to hear that you having interest in different field. But our need is important not interest. After getting good job you should resign from present job. As far as teaching field is concerned you should have graduation degree in geography with B. Ed. Then you can apply for primary teacher in any govt school. For becoming lecturer you need to have post graduation degree with minimum of 55% followed by UGC-NET in geography subject. Then you are eligible for apply in govt college.

Teaching job is only for really dedicated and interested people to take the teaching as a profession. Unless otherwise self interested in teaching the interest will not come in one's mind. As already in a Government job, you can think of about your future as you can get job security, pension benefits etc., But if you project yourself in a teaching profession you should first of all have real interest in teaching, then qualification such as B. Ed, which is a must for teacher in Government schools. More over your opted subject is geography, which is really have a good opportunity as the teachers for Geography are very less in nowadays.
You chek with the local teaching people about the qualifications etc., availability of teaching seats etc., and then you quit your present job.

Presently You are working in Government Sector it is a good point because almost every people want to join a government job. But it is a big question, are you satisfied with your job or not? If you are satisfied with your job then you can teach Geography after your duty or part-time time as a tutor. I have seen there are a large number of people teaching students after their main duty.