I usually pray al dhor and al asr, and sometimes al maghreb and al isha, in the office. However while I try to maintain al wodou' to last for at least al asr prayer often time I must repeat it. I refreain from going to the bathroom to have my wodou' last, but this is sometimes impossible to maintain. The problem is in the condotion of bathrooms in my office which lack privacy and are used by many persons who do not have follow the standards of al tahara. Repeating my wodou' becomes difficult in this case. Can I pray al dhohr and al asr together with niyyat al jama' and al taqdeem to avoid having losing my wodou' and suffering from my doubts that my repeated wodou' will not secure the level of tahara I should have? Thanks you.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

It is unlawful to combine two prayers without a sound excuse like being on a journey, or being sick, or because of rain and any similar excuses.

As for what you mentioned, it is not a sound excuse as you can avoid impurities at the time of prayer and pray ‘Asr prayer at its prescribed fixed time.

Allah knows best.