For a long time storage of nucleic acids, RNA particularly, the best way to keep it as sodium acetate-alcohol precipitate. In water solution, RNA is more stable at low acidic pH (4-5). Increasing ionic strength and chilling increase time of storage.  

Tris-EDTA buffer is commonly used to store DNA and RNA. EDTA is metal chelator that can inhibitor nuclease by binding to and making inaccessible the Mg2+ these enzymes often require for their activity. The enzymes are also less active at pH 8, see link.

Hope you find this useful.

https://www.ncbi.nlm.nih.gov/pubmed/8724437

Thanks George for the article. I am going to read it. 

Hi, In fact, DNA dissolves best at alkaline pH so commonly we store DNA in buffers like 10 mM Tris-Hcl pH 8.5, or Tris-EDTA pH 8.0, also if we try to store the DNA in water then it is quite prone to acid hydrolysis which is a known fact, whereas the storage of RNA are often & mostly done in RNAse-free water but it is not a real good practice as you will find a definite drop in your RNA concentration over the time even at -80 C storage, which definitely is very painful when you read your RNA concentration later on. So, usually for RNA storage, divalent chelators are used like EDTA or you can use even Tris-EDTA buffer (10 mM Tris with 1 mM EDTA), it is the most appropriate way to store RNA. But you may aware the hectic and bizarre issue to dissolve EDTA powder to make its desired molar solution in buffer having a proper pH, so I would rather recommend to purchase R-T-U RNA storage buffers which use to contain either sodium acetate or ammonium acetate and both act as RNA stabilizers. These buffers can be used instead of the elution buffers or RNAse-free water elution step during the RNA extraction protocol. The main purpose to use monovalent or divalent accompanied buffers for RNA storage to avoid any possible heat induced RNA strand scission along with their role in destabilization of nucleases, which may even occur when you take your RNA out from -80C to perform further downstream applications, which usually not occurs in DNA case due to the enhanced stability of this molecule even at room temperature.

I keep both in water as EDTA can inhibit the following PCR protocols. RNA in DEPC treated water at -80C. Even one night at 4C is not recommended. 

If you want  to  preerve DNA or RNA for long time, you should use the appropriate buffer. If the DNA or RNA was used to next  experient ( pcr or restriction enzye digestion), I suggest water or ultrapure water (RNA in RNAse-free water).

As all have said

10mM Tris 1mMm EDTA  pH 8 for DNA

10mM Tris 1mMm EDTA pH 7.5 prepared in DEPC treated water forRNA

I use TE buffer to preserve DNA.RNA in water as all said.

Thanks.Priya

i would never us ewater for dna or rna storage particularly for primers and rna. As said above edta takes out magnesium so nucleases cannot work, Also water absorbs co2 from the air and becomes acidic. this will depurinate your samples and they will degrade

Most of the deoxyribonucleases require divalent cations so that EDTA-containing solutions (e.g. TE buffer) is recommended for storage of DNA samples.  However, as far as I know, RNase A does not require divalent cations.  Therefore, I do not use DEPC-treated water for storage of RNA samples.  

     Since TE containing 1 mM EDTA does not appear to severely affectt PCR, I usually use TE for storage and dilution of primers and DNA templates.

You can stock in TE buffer and for working solution use DNase free water .

For a long time storage of nucleic acids, RNA particularly, the best way to keep it as sodium acetate-alcohol precipitate. In water solution, RNA is more stable at low acidic pH (4-5). Increasing ionic strength and chilling increase time of storage.  

In folk-theory, DNA  is safe at pH's near 8.0,  and RNA, below pH 5.0

Often the fear is ambient DNases and RNases being allowed their respective degradative activities by way of divalent-metal co-activation (e.g., Mg++ mainly). 

Additionally, with RNA, nucleophilic self-attack by deprotonated 2' hydroxyl group(s) under basic conditions in the presence of divalent metal cations is also suspected. Sometimes this is worthy of being fearful of.  The more concentrated the sample, the less it is prone to degradative processes.

Environmental DNAses and RNAses are cited as culprits in most situations,  Freeze-thawing is another misunderstood mythos as well.  Sometimes it is deleterious, other times -- not at all.  This is still an ongoing discussion. 

Water because RNA is more stable in water

In pure water RNA molecules are partially denatured and are more sensitive to nucleophilic attack by, let say, hydroxyl and by nucleases. Thus, RNA is more stable under physiological conditions (for example, in PBS) than in pure water.

Also not that it is difficult to control the pH of ultra pure water.  Indeed, it is rather difficult to measure it's pH since pH is measured using fee ions.

I want to second Yuri's excellent suggestion: for long term storage, keep the RNA precipitated in sodium acetate-ethanol.

Short-term storage (weeks) at 4°C in Tris-EDTA

Medium-term storage (months) at –80°C in Tris-EDTA

Long-term storage (years) at as –80°C as a precipitate under ethanol

Long-terms storage (decades) at –164°C or dried

Thank you all really for your response.  It was really very helpful for me. 

For next generation sequencing, which is best to dissolve DNA? TE or Nuclease free water and why?

DNA is pretty stable (months) in frozen 1 mM EDTA (-20*C) or nuclease-free water at -80*C. Chemical composition of the DNA (RNA) storage medium depends on the following buffer solution you are going to use. Its have to be compatible.

Shilpa, since EDTA not only inhibits DNases but also other enzymes that need metal ions for activity, I would suggest to use water or a neutral buffered solution without EDTA, like 10mM Tris-HCl at pH 8. Buffered conditions are definitely favorable for long-term storage, DNA in water can be subjected to acid hydrolysis.

What is the procedure to remove DNAse/RNAse from Tris-Edta Buffers? Thanks

Dear Ondrej,

Tris-EDTA buffer at pH 8 made in DEPC treated water is safe.