quat- vb. "fill" (WJ:392), future #quantuva "shall fill" (enquantuva "shall refill") (Nam, RGEO:67) Irrespective of the prefix en- "re", the form enquatuva (VT48:11) displays the expected future tense of quat-. The Namárië form enquantuva seems to include a nasal infix as well, which is possibly an optional feature of the future tense. On the other hand, PE17:68 cites the verb as quanta- rather than quat-, and then the future-tense form quantuva would be straightforward.
Quenya
-uva
fill
quat-
fill
quanta-
fill
quanta- (2) vb. "fill" (PE17:68), cf. enquantuva "will refill" in Namárië. This verb seems to spring from a secondary use of the adjective quanta "full" as a verbal stem, whereas the synonym quat- (q.v.) is the original primary verb representing the basic root KWAT.
-uva future tense ending. In avuva, caluva, cenuva, hiruva, (en)quantuva, (en)tuluva, laituvalmet, lauva, maruvan, termaruva, tiruvantes. A final -a drops out before the ending -uva is added: quanta- "fill", future tense quantuva (PE17:68). A verbal stem in -av- may be contracted when -uva follows, as when avuva is stated to have become auva (VT49:13). Origin/etymology of the ending -uva, see VT48:32. In VT49:30, the future tense of the verb "to be" is given as uva, apparently the future-tense "ending" appearing independently, but several other sources rather give nauva for "will be" (see ná #1).